Servant

Servants (サーヴァント) are Heroic Spirits and Divine Spirits summoned by the Holy Grail for the purpose of competing under Masters in the Holy Grail War.

Nature
Servants are Heroic Spirits made into special familiars of the highest rank that are bound to the Master. Pure Heroic Spirits, the "main body" in the Throne of Heroes, can only be summoned by the World, and summoning even one is considered to be a miraculous occurrence. Differing from the normal definition of familiars that can be likened to minor mascots unable to be stronger than their masters, Heroic Spirits are the most powerful of beings with which even the five magicians would never be able forge a contact. Rather than it being a hard process to summon them or the fact that they far surpass magi, it is their intrinsic nature in that they are beings beyond magecraft. Magi can perform rituals to borrow their power to mimic them, but cannot summon actual Heroic Spirits themselves.

Even the Holy Grail lacks the power to summon a true Heroic Spirit, so the process is facilitated by summoning them into one of seven vessels prepared beforehand. The Greater Grail makes a copy using information from the "main body" of the Heroic Spirit, an "emanation", that returns to them as information, in the form of a soul, upon the death of the Servant. Disconnected from the "main body", they are able to know of the actions of the Servant through records, as if reading a book. Due to this, any Heroic Spirit summoned in multiple Holy Grail Wars will lack knowledge of previous summonings. The only exemption is King Arthur due to her unique circumstances.

Similarly as to how demons require a form invented by humans in order to take shape, Heroic Spirits need a form to exist in the world. The vessels, classes, act as their temporary name and method of existing. Acting like a "passport to the present", the vessel prepares them for their role as a familiar in advance, allows them to take on that role to help them take form, and brings them forth into the world. Each class identifies only the core skills of the Heroic Spirit because replication of all their ability is impossible. Their main traits align with the class and are given form, matching the principal nature of the class. Only heroes matching the attributes of the classes are brought forth, allowing them to be summoned into any reflecting their abilities.

Although too powerful to be controlled by humans, they are bound by three Command Spells, representing the Masters' "right to rule" over them, with obedience towards the Command Spells being the "absolute condition required for materialization." Due to the prospect of having a wish granted by the Holy Grail, it also serves as incentive to cooperate with the Master, as well as requiring them for energy upkeep and acting as their anchor to the world. Killing them will normally go against their purpose, but the Command Spells protect the Master from those who would kill them to seek out one who would be more suitable.

Characteristics
Servants are beings able to switch between a Spiritual Body and Material Body at will. While in spiritual form, they cannot be easily detected by enemies, due to being invisible to the naked eye and most forms of scrying, or affected by physical interference. They can travel where they please without being impeded by walls, but they also cannot carry anything in that state. Their senses are limited to spiritual sensations, so they must materialize in order to fully experience normal senses when sharing a visual link with their Master. Their upkeep cost is low when not materialized, so many Masters prefer them to stay in spirit form to lower the cost on themselves. Depending on the disposition of the Servant or a special case like Saber, such an order may be impossible. It is also hard for them to affect a Material Body in that state, so they must materialize to properly engage in combat.

While they may bleed and take damage to their organs, their true being resides in a Spiritual Core they obtain upon first materializing. Their Material Body envelopes it, and damage must be inflicted to it in order for them to be defeated. It gradually diminishes under magical energy expenditure and while sustaining bodily damage, and their expenditure will escalate under such conditions. If it is damaged through powerful magical energy, curses, or Noble Phantasms, it will be destroyed, meaning that the Servant can no longer stay materialized. The heart and head are directly connected to it, so they are a Servant's greatest weaknesses. Sustaining damage will significantly weaken it, with some Servants having it instantly destroyed and some with skills like Battle Continuation being able to at least temporarily sustain themselves.

While they have Material Bodies like humans, the composition is drastically different. They are of a much higher magnitude, so it is normally impossible for portions to be transplanted onto a human. Shirou Emiya is able to obtain Archer's arm due to them being the same person. Normally the recipient would die of shock, but being even closer than twins allows the surgery to succeed. It is still too much for him even in that case, so being connected to it slowly kills him. Sieg, a homunculus, obtains Siegfried's heart, gaining the ability to transform and a longer lifespan, yet his body is consumed by memories and Siegfried forces until no longer the same and ending transformed into a dragon.

Possession
It is possible for a Servant to possess a human, fuse with a human to become a Demi-Servant (デミ・サーヴァント), and for a human to act as a receptacle for the facilitation of the summoning to become a Pseudo-Servant (疑似サーヴァント). Normally the souls of Heroic Spirits would overwhelm those of humans, making it impossible for them to intermix and grant a human the powers of the Heroic Spirit. Pure souls like those of homunculi can have a better time accepting their power and withstanding transformation of the flesh. The act of a Heroic Spirit possessing a human for even a single second can be called a miracle in itself.


 * Possession
 * The Greater Grail is able to make the process work for Ruler by searching for a match with a compatible physical build, spiritual build, personality, and magical energy. The possession seals the target's former personality and spiritually installs the Heroic Spirit. After receiving clearance from the host personality, it performs a "cross-domain base anatomy backup" to be able to restore the target even if Ruler is killed. It adapts the physical and spiritual build, grants the Class Skills, grants knowledge of Heroic Spirits and the modern era, and inputs other required data. Overwriting and merging with the target's body and personality, Ruler notes having most of the target's memories. Rather than two personalities in one body, it is more that they merged into one.
 * Through an intermediary like part of a Heroic Spirit's body or a related catalyst implanted into someone's body, it can be possible to call down the Heroic Spirit directly from the Throne of Heroes to inhabit their body. The process requires something of great power like a Command Spell, and the transformation will only last a few minutes. Due to possessing Siegfried's heart, his soul, and special Command Spells, Sieg is able to act as a shell for the body of Siegfried, retaining his own personality while being able to utilize Siegfried's abilities.
 * Some Servants possess abilities that can cause a strong effect on the body of the Master, so they are able to share a physical body with their Master. The Master can become close to an immortal existence for the duration of the Holy Grail War by not being able to die until the Servant dies, but it does not increase their power to the point where they would be able to fight a greater existence than an Assassin-class Servant.


 * Demi-Servants -
 * The process of creating Demi-Servants is an expiriment created by the Chaldea Security Organization. Shielder is the result of a hasty fusion between Mashu and Galahad.


 * Pseudo-Servants
 * Pseudo-Servants are the result of Heroic Spirits that cannot become Servants for some reason, so they are instead summoned by using a human body for their vessel. The resulting Servant cannot be called either individual, but rather a combination of the powers of both individuals mingling together that add abilities not present in the original Servant. The thoughts and personality may conform to that of the human vessel as well. Multiple Pseudo-Servants have been confirmed in the Grand Orders, including Zhuge Liang (Lord El-Melloi II).

Alignment
All Servants have an Zokusei (属性), a status showing a clear representation of the mentality of the Servant, differing from the elemental alignment of magi. It is broken down into two parts, a combination of the principles they consider important and their personality. Principles are reflected as Chaotic (混沌／渾沌), Lawful (秩序), and Neutral (中立), and their personalities are reflected as Good (善), Evil (悪), and Neutral (中庸). Berserker Servants have also displayed Insane (狂化) as a "principle", and Mad (狂) and Reckless (暴走) as their "personalities." Differences in personality will not result in major discord, but differing principles can make Servants resolving their differences of opinions difficult. While two Servants may have the same personalities as "good", like King Arthur and Gilgamesh, their Lawful and Chaotic principles lead to differing opinions.

Others:
 * Elizabeth Báthory (Berserker) - Insane Reckless
 * Heracles - Chaotic Mad
 * Lancelot - Lawful Mad
 * Nursery Rhyme - Variable depending on Master
 * Nero Claudius Caesar (Bride) - Chaotic Bride

Upkeep
Servants must maintain a certain amount of energy to remain materialized and fight, and they must have an anchor to the world, their Master or another physical being, in order to remain in the world. Their current strength is reflected by their current stores of energy, so they will lose strength as they lose energy. The Grail itself provides most of the upkeep for Servants during the duration of the Holy Grail War, so Masters, granted Magical Paths to supply energy, do not need to provide vast amounts of energy normally. More energy intensive Servants like A-rank Servants and Berserker-class Servants can still pose a great threat should they not have the ability to provide their upkeep, even draining them to death in the case of Berserkers. Those who are cognizant are able to throttle the energy they intake, keeping their output to a minimum or using only their own stores when their Masters are unable to provide their full cost.

If the Servant is without a Master, has issues with the Magical Paths, or has a Master unable to supply energy, they must supplement themselves elsewhere. As Human Spirits, they have the ability to consume the souls and minds of people and convert them into energy. Their basic abilities do not change from such nourishment, but they become tougher as their magical energy capacity increases. They can also intake semen or blood for energy depending on their method of processing it. Places like Ryuudou Temple can naturally allow them to subside longer, and draining directly from leylines is possible for some. With a full stock of energy, they can subside for a time even with the constant cost of upkeep, and they regain some energy from their own magic circuits daily. Remaining in spiritual form can decrease their upkeep, and while in material form, dematerializing weapons and armor can help cut it somewhat. Food can be converted to supply some energy, and sleeping can stop the consumption. This only helps when no action is taken due to even a single battle using upwards of twenty times as much energy as simply existing, so such methods are only stop-gaps compared to taking in souls.

Even having a full supply will not help a Servant should they lose their anchor to the world with the loss of their Master, so they must quickly seek out another contract. While normally not much of a burden, their energy noticeably drains by the second without one. Depending on the amount of energy and upkeep cost, they may only be able to stay materialized for a brief time. Saber can manage only two hours, while Caster can last two days with a full supply of energy. Those with Independent Action are able to subside without Master support for longer than others, allowing them a better chance to seek out another contract. Much like the class container, their anchor is a "passport to the current age", so losing that will mean being forced to return to the "outside." They cannot form proper contracts with other Servants, as spirits cannot link spirits to the world. Caster is able to summon Assassin, but it is an improper summoning with several complications. Rather than her being his anchor, it is the mountain gate, so he cannot leave the area. Without a Master, they are no different than regular spirits and may be affected by the Church's scripture.

It is possible to remain materialized as a normal familiar after the Holy Grail War ends, but it greatly increases the cost without active support from the Grail. Rin Tohsaka, a superior magus. has no issue in providing for Saber's upkeep, Noble Phantasm usage, and Shirou Emiya's Reality Marble at the same time during the Holy Grail War, but in-turn requires the majority of her energy and Shirou's help in keeping Saber materialized after it ends in Unlimited Blade Works. The only one easily able to maintain a Servant is Sakura Matou after becoming the Grail in Heaven's Feel, granting her a limitless supply that easily allows her to maintain Rider. Gilgamesh incarnating allows him to exist indefinitely by granting A+ Independent Action, allowing him to exist for ten years with no issues. Ruler becomes incarnated through another method, allowing him to exist for about seventy years.

Knowledge
Those summoned as Servants are given the minimum information required to allow them to fit into any era. No matter how ancient the Heroic Spirit, they should understand a number of concepts that were not known in their time. The idea that Saber may be shocked about the immediate world initially worries Shirou Emiya, but the knowledge makes such worry unnecessary. Irisviel von Einzbern first believes that Saber may find flying in a plane to be an amazing experience, but it instead seems less than expected to her. Flying in a plane is also mitigated due to her Riding skill that could potentially even grant her the ability to fly it. While not given enough information to actually drive modern vehicles, higher ranks of Riding grant the ability to manage such through intuition even if they do not actually recognize what each separate control of a vehicle will actually perform what action. Conversely, even though Ruler understands the basic principles behind the concept of a plane, she is unnerved by the idea of a mass of metal flying through the sky and only has the relief that it did not fall out of the sky after landing. With language, Rider displays the ability to speak English to his Master, Waver Velvet, and also speak Japanese to Taiga Fujimura, allowing him to easily translate between the two.

The knowledge is not all-encompassing, so concepts may have to still be explained to them. Rider is shocked at the true scope of the world compared to the area he had conquered in life, and needs to have certain areas shown to him on a map. He enjoys spending his time learning about different aspects of the world such as wars since his time, and details like the price of a stealth bomber are not immediately known to him. Saber does not understand the idea of dating until it is specifically explained. They are granted knowledge on the ritual itself, but only as much as the outside Masters are told. They do not know of its true purpose in being a method requiring all seven be sacrificed to reach the Root, only believing it to be a war for a single wish. The knowledge can change upon the nature of the war changing, allowing knowledge of the two teams of Servants and factions of the Great Holy Grail War to be given to them.

They are not granted knowledge on other Heroes through the Grail, but rather from knowledge gained within the Throne of Heroes. Witnessing traits of other Servants can allow them to deduce their true names with the knowledge even if they are from incompatible eras. Aberrations like Saber, who is not part of the Throne of Heroes due to her circumstances, are able to identify those whose legends would have been known to them in life, such as Cú Chulainn, but cannot identify the legends of later Heroic Spirits like Gilles de Rais even after being directly named.

Class Card
Class Cards (クラスカード), also called Servant Cards (サーヴァントカード), are artifacts created for the Ainsworth Holy Grail War, a system of summoning Heroic Spirits similar to Servants. Differing from allowing a Heroic Spirit to manifest, the cards encapsulate the Heroic Spirits, used by the participants of the Holy Grail War to fight amongst each other.

Much like the Servant system, seven cards are summoned during each Holy Grail War, corresponding to one of seven classes. The cards have a portion of the Heroic Spirits' power sealed inside them, and it can be said that they are the Heroic Spirits themselves. They draw out the power of Heroic Spirits, allowing either a Mystic Code or the user's own body to act as a medium for the Heroic Spirit's power. Overwritten by a fraction of the Heroic Spirit's power, they are able to fight others with that power. Meant to be utilized in the Ainsworth Holy Grail War, the Mage's Association of Illya's world is unable to analyze them in any manner.

One part of the process of creating the Class Cards robs the Heroic Spirits of their reason and pollutes their egos by passing through the Ainsworth's "box." Only the Gilgamesh Archer Card shows the ability to retain its ego without being polluted, allowing Gilgamesh's personality to overwrite the user. The cards can manifest as their Heroic Spirits by gathering magical energy from the land. They possess no reason, and they possess a deteriorated, blackened appearance. The Heroic Spirits form around their Class Cards, utilizing them as their heart. Compared to their Servant counterparts, the blackened Class Cards have several "errors" from being stained, such as Noble Phantasms and skills being ranked down. Their parameters are generally decreased by one or two ranks, and their loss of reason reduces their fighting ability and combat skill. They are considerably weaker due to these factors.

The participants of the Holy Grail War and possessors of Kaleidostick utilize the power of the cards with two methods. With the Include: Limit Expand method, it temporarily materializes the weapon or Noble Phantasm of the hero by overwriting a Mystic Code until the Card is Unincluded. The true purpose of the Cards is to temporarily become a hero by accessing their full abilities. Install: Phantasm Summon grants the Noble Phantasm, appearance, and skills of the Heroic Spirit. The user obtains a "fraction of their power", their own existence "overwritten" by that of a hero's existence. There is also Kaleid Install, both Kaleidostick wielders using a single card together, utilizing the weapons of a Servant.

Grand
The original purpose of the classes was for a ritual in which seven of the greatest Heroic Spirits were summoned by the Counter Force in order to prevent the extinction of mankind by a single "enemy". This system was later adapted for the Holy Grail Wars by humans, resulting in summoning rituals that paled in comparison. The Heroic Spirits that were part of the ritual to defend humanity are known as Grand Servants, beings of much higher standing than regular Servants. Although the Grand Servants are chosen from the pinnacle of Heroic Spirits, the overwhelming strength that the Grand Servants display against Servants is not because they themselves are that much stronger than other Heroic Spirits, but because they are summoned as an entirely different entity by the World itself.

Solomon of Fate/Grand Order is known as the Grand Caster.

High-Servant
High-Servants (ハイ・サーヴァント) are Servants created by BB by combining several of the "goddesses series" of Servants into each of her Alter Egos.

Summoning
Masters summon their Servants at the start of each ritual. Different system possess different means of facilitating the summoning.

Fuyuki-based systems
Under systems based upon the Fuyuki ritual, there are several factors that determine which Heroic Spirit the Master will summon. It is general that the seven participating Masters are all magi due to requiring basic magecraft to properly perform the summoning, but the quality of the Masters does not matter so long as the most basic summoning requirements are met to fill out the Grail's requirement of seven Servants being manifested. Upon selecting the Masters, the Grail distributes the massive amount of magical energy it has gathered among them to facilitate the process.

Performing a summoning ritual facilitates the process in which the copy of the Heroic Spirit is brought into the chosen class container. Most Masters will prepare a catalyst with which to summon their desired Heroic Spirit, but it is not absolutely necessary. Without a specific artifact, the Grail will, rather than base it on their power, chose a Servant based upon similarities to the summoner's own nature. When choosing based upon power with a catalyst, bad compatibility may make forming a bond impossible, bringing about hardships without being able to have faith in each other. When allowing for a good affinity, it may bring forth a weaker Servant, and it is possible that a single mistake could rouse bad feelings between them due to the resemblance in their personalities being so close.

Summoning ritual
While summoning ritual (儀式の召喚) are generally specific, their main goal in the Holy Grail War system is to act as a precaution to create a bond with a perfect, reliable Servant. They really only require a summoning circle, even if unskilled, and a catalyst can bypass the need of chanting a spell. Doing so can create aberrations like Gilles de Rais being placed into a normally unsuitable class or King Arthur having a bad connection with her Master that does not allow her to receive magical energy through normal methods. Flatt Escardos is a complete anomaly in that he is able to complete the ritual without even meaning to summon a Servant, simply by "fiddling" with the magical energy in the area. The connection to his Servant is spontaneously established, and it is unknown if it can be called a miracle, luck, or an achievement of his own latent potential. It is possible to specify in the summoning ritual that the Servant be placed under the Berserker class for those familiar with the workings of the Grail System. By adding in a specific line, Zouken Matou and the Einzbern family, as members of the Three Founding Families, were able to choose the class during the Fourth and Fifth Wars. In the Great Holy Grail War each faction has a summoning ritual according to the color that represented.

Catalyst
Catalysts (触媒) are symbols and holy relics used to attract the desired Heroic Spirit. Requiring something with a connection to the hero, it can be anything from a sword, armor, a talisman, or even their bones. While something like Rin's Pendant is an artifact holding great power on its own, it is unable to help summon a Servant. If the catalyst is one that is particularly weak, or if it is one with a connection to many different Heroic Spirits, the Heroic Spirit among the candidates that has good affinity with the Master will be chosen. Some are those that have only been connected to a single Heroic Spirit, allowing them to be brought forth regardless of affinity with the Master.

Catalysts are extremely valuable, and it can take much effort depending on the Servant the Master wishes to summon. The Mage's Association, having been collecting the esoterica of thaumaturgy for generations since ancient times, has a grand number of catalysts "numbering among the stars." Kayneth El-Melloi Archibald is able to order a relic from Macedonia, while the Einzberns have to specifically have Avalon excavated from Cornwall. Within the Fate/Apocrypha world, the spread of the Holy Grail War system means many catalysts quickly disappearing over seventy years and numerous Grail Wars. Especially those of Gilgamesh, King Arthur, and Alexander the Great are scattered and become lost over time, and Yggdmillennia specifically collects desired artifacts over decades to procure enough excellent Heroic Spirits. The Association still has enough even then to easily provide seven catalysts to their Red Faction on a short notice.

Examples of catalysts include:
 * Angra Mainyu: Avesta, an old scripture and foreign folklore
 * Alexander the Great: Shard of cloth from his mantle.
 * Astolfo - Glass bottle which had a liquid stain left on it.
 * Chiron - Ancient arrow blackened by blood.
 * Cú Chulainn: Jewel on which is engraved an original rune inscribed by Cú Chulainn that had been crafted into earrings.
 * Diarmuid Ua Duibhne: Unknown, prepared by Kayneth El-Melloi Archibald in haste after his original artifact is stolen.
 * EMIYA: Rin's Pendant, a one-of-a-kind jewel kept by Emiya as a keepsake of his unknown savior over the years. Differing from normal, it is not the pendant Rin owns in the present that acts as the catalyst. Emiya is instead a case where he holds a catalyst with a connection to his summoner.
 * Frankenstein - Frankenstein's blueprints
 * Gilgamesh: The fossil of the first skin shed by the first snake after consuming the immortality elixir, and a discarded key to the Gate of Babylon.
 * Gilles de Rais - François Prelati (Possible catalyst)
 * François Prelati - Own living body
 * Hassan-i-Sabbah: Since Hassan is the origin of the word Assassin, the class of Assassin itself is Hassan's catalyst.
 * Heracles: The Axe-sword, a slab of rock from a temple of Heracles.
 * Jack the Ripper: Jack the Ripper's knives
 * Jack the Ripper (Symbol of madness): Replica Jack the Ripper novelty knife
 * King Arthur: Avalon, the sheath of Excalibur.
 * Lancelot: Unknown, Zouken Matou mentions obtaining the "perfect relic" for Kariya Matou.
 * Medea: Literature from Colchis with ties to Medea.
 * Medusa: Mirror dug up from a temple in Eritrea, an item with ties to an old Earth goddess of Greece. It is noted to have been a weak catalyst to Medusa, so Sakura Matou's similar personality plays a role in the summoning.
 * Mordred - Shard of the Round Table
 * Ramesses II - Nefertari's necklace. Ramesses II had also noted that there were several other objects that could have served as catalysts such as the remains of his war chariot, his bow used in the decisive battle against the Hittite King, the epitaph of the contract he exchanged with the Hittites, or something that had been plundered from his own mummy.
 * Richard I - Unknown, it was an obtained by Cashura, who intended to summon King Arthur, but due to the incomplete nature of the summoning as a result of his death, Richard I was summoned mistakenly instead.
 * Sasaki Kojirou : The mountain gate.
 * Siegfried: Bloodstained leaf of a Sacred Fig tree.

General catalysts include:
 * Remnant of the : Heracles,, Medea, , or other crew members
 * Shard of the Round Table - King Arthur, Lancelot,, Gawain, , , Mordred, or other members of the Round Table.
 * The, the symbol of the

Servants summoning Servants
It is also possible for some Servants to bring forth other Servants under limited conditions with their own abilities and Noble Phantasms:
 * Alexander the Great's Ionioi Hetairoi allows for tens of thousands of Servants to be summoned within the Reality Marble. Only one can be summoned outside of it due to the corrective impulses of the world.
 * Okita Souji's Flag of Sincerity can summon a small squad of Servants to fight temporarily.
 * Shakespeare's First Folio can bring forth Servants as "characters", but they are weaker than a Caster-class Servant in function.
 * Scáthach can summon Servants with her Original Runes, using herself as the catalyst.
 * Toyotomi Hideyoshi's Sunomata Castle can summon a number of his retinue as Servants, but they can only fight outside of the fortress for a brief period due to their energy source being located inside.

Limitations
Within the Fuyuki Holy Grail War system, there is a rule making only the summoning of Western Heroic Spirits possible due to the Holy Grail being a Western, Christian, concept and that the summoning system was created in the world of Western magi. Sasaki Kojiro of the Fifth Holy Grail War is a complete aberration in many ways. Other systems like the Moon Cell Holy Grail War have no such restrictions. Under normal circumstances, the Fuyuki ritual is made for the summoning of only "pure Heroic Spirits", so with the exception of Hassan-i-Sabbah, those who are "mixed spirits" "who only have the aspect of a Heroic Spirit" cannot be summoned. Through the induction of Angra Mainyu into the Grail after the Third Holy Grail War in the main timeline and the alterations made by Darnic Prestone Yggdmillennia in the alternate timeline of the Great Holy Grail War, it becomes possible to summon those with anti-hero aspects. That limitation is not present in other Holy Grail Wars like the Moon Cell Holy Grail War.

Divine Spirits cannot be summoned normally under most systems. Due to their nature, it is nearly impossible for them to manifest in the current world.
 * Fuyuki - Within the Fuyuki system, summoning full Divine Spirits is beyond its ability, and it is said the capability to reproduce phenomenon of that level would render the Holy Grail unnecessary in the first place. Only through losing their Divinity did Chiron and Brynhildr become existences able to be summoned, and Medusa, more of a Divine Spirit than a Heroic Spirit, became applicable only after her Divinity decreased through becoming a monster. The Einzberns were confident in their ability to circumvent their own system to bring about the god Angra Mainyu, but he was a Heroic Spirit instead.
 * Moon Cell - Within the Moon Cell, the recorded Divine Spirits are considered to be non-human Heroic Spirits and stored in its Servant records. Though none are summoned for the proper Holy Grail War, BB creates the Alter Egos from combing several goddesses into each of them.
 * FATE - Under the FATE system, it is possible for Divine Spirits to be summoned, but Dr. Roman explains that such a thing should be impossible.
 * Class Cards - Under the Class Card system, Julian Ainsworth has encapsulated the power of Thor into a Class Card.
 * Imperial Holy Grail - Under the system used by the Nazis in Strange Tales of the Imperial Holy Grail, it is possible to summon pseudo-Servants including Divine Spirits in a limited capacity.

Strength
Servants have six primary statistics that make up their overall strength:
 * Strength (筋力): Bodily might in terms of power.
 * Endurance (耐久): How much damage one can withstand.
 * Agility (敏捷): Quickness and speed of reaction.
 * Magical Power (魔力): How much magical energy can be handled.
 * Good luck (幸運): The quality of one's luck.
 * Noble Phantasm (宝具): The strength of the Noble Phantasm one owns. While the ranking will often match their strongest Noble Phantasm, it will sometimes only reflect a secondary Noble Phantasm, or display a ranking higher or lower than their available wares.

Each of the statistics and skills are translated into specific parameters, reflecting the individual ability of each Servant. They display strength and speed far beyond normal humans, showing in battle displays likened to a "dimension that is completely at odds with the physical laws of this world." Simple hand-to-hand combat between two Servants is enough to wreck a city street in a manner able to be compared to having been carpet-bombed, damaging the ground with only their footfalls, cutting metal with only the backlash caused by their weapons clashing, and tearing away iron from simply brushing against it with weapons. The usage of their Noble Phantasms can easily leave an area in complete ruin, some displaying the capability to easily wreck part of a city with minimum usage.

Both their movement speed and dexterity is enough to make them invisible to the human eye, looking like a breeze of wind when running past and only leaving the aftershocks of their attacks to be felt by onlookers. Compared to even a top-class motorcycle like Saber's V-Max able to reach over four hundred kilometers per hour, the dexterity of a Servant places them far above it both maximum acceleration and speed, and they can rival a jet fighter in speed with proper footwork. It may be still advantageous to use a motorized vehicle in a pursuit due to it only relying on its fuel rather than using their own energy up while running on foot. The speed of bullets travelling faster than the speed of sound poses no threat, unable to surpass the speed with which they wield their weapons, and those with greater dexterity can easily deflect them with their weapons. Not bound by normal logic, they are able to move up the sides of buildings simply by kicking off the sides.

Even the smallest of Servants will have little issue in carrying a person, and Rider, casually copying something out of a comic, is able to lift a vehicle from a construction site to slam down on to her opponents. Even those who are physically weak compared to others like Caster-class Servants show great feats of strength, Gilles de Rais displaying grip strength enough to easily crush a human skull and Medea severing an arm with a ritualistic dagger unable to normally even be considered lethal to a regular human.

Masters who have made contracts with Servants have the ability to read out the status of a Servant with powers of clairvoyance. It is a unique ability granted by the Grail that summoned the Heroic Spirits, so it cannot be used by those without a contract. They can see through the abilities of the other Servants and compare them to those of their own, so that they can guide them as efficiently as possible in battle situations. Tokiomi Tohsaka owned a book that provides a similar ability, but it is useless to a full Master. It was passed on to Rin Tohsaka after his death, and she gives it to Shirou Emiya because he lacks a proper connection to Saber. The book itself is blank, but simply looking at a random page gives him an image in his head that allows him to look upon all known status of Servants in the War. Reading the book will give him new details any time he reads it, and Rin says that he will be able to identify Servants from intuition without using the book after he gets used to it. It is reflected in-game as the Servant status screen.

Factors
The strength of the summoned Servants depends on various factors. It is ideal if the Servant can wield their original power as a Heroic Spirit, but it is also possible that they can even surpass their original selves in the case of the attribute enhancement from Mad Enhancement of the Berserker class. It is also possible to obtain abilities from Class Skills they did not originally have in life, such as Riding modern vehicles, or have their own attributes strengthened by their classes' natural attributes.


 * Cultural Sphere (文化圏) - The Land (土地) in which the Servant is summoned and the Recognition (認識) they receive there are two factors that play a role in their strength. The closer they are to the stage of their legend, a geographical boost, and the more that they are known makes them "stronger", bringing them closer to the strength they had in their legend and providing them with more of their equipment displayed in their legend. Depending on the circumstances, it is possible it can bless them with additional Noble Phantasms. The boost from recognition alone is not that large in making a difference in power as when Rin Tohsaka is speculating on Gilgamesh's ability to overwhelm other Servants. Land plays a greater factor with Cú Chulainn, Heracles, and King Arthur being three heroes around the same level of strength when summoned in Europe. Each would be strengthened in Europe and benefit most greatly in battle in their home country, though Heracles' fame would allow him to display excellent power throughout all of western Europe. Cú Chulainn, gaining zero influence from not being known as well in Japan, does not fully display his "shining existence" on par with them while in Fuyuki, but would anywhere else in the world. He would obtain several benefits from being summoned in his homeland, Ireland, and outfight Diarmuid Ua Duibhne, who would have an advantage when both are unaffected by the cultural sphere and have other factors at play. Vlad III gains a great boost in Romania, placing him on the same level as those famed heroes, and Semiramis gains her maximum fame while in the confines of the Hanging Gardens of Babylon.
 * Magic energy of the Master - The more powerful the magical energy of the Master, the greater the Servant will be able to reach the strength they displayed in their legend. If they cannot provide proper energy or if the Servant lacks a Master for a time, their parameters lower in proportion. If it is a lack of energy, unknown factors will lower parameters and skills with some Servants, while the Master's way of life may affect others. King Arthur, serving under several different Masters, displays a number of different sets of parameters due to fluctuating levels of energy. Under Shirou Emiya, she receives no energy because his Magical Paths are obstructed and cannot display her full strength. Kiritsugu Emiya is able to supply energy to have her be stronger than under Shirou, but her luck is affected by his personality due to still not providing enough energy. Her Riding is increased one rank higher than normal for an unknown reason. Rin Tohsaka is an excellent magus able to allow her to unleash her full abilities without being affected. Two Servants who would be balanced differently under other circumstances may find the balance tipped when one has better Master support.
 * Container Parameters: Unmodified by the strengths and weaknesses of specific Heroic Spirits, the containers of the seven standard Servant classes of the Fuyuki Grail War possess known base parameters. The parameters of the containers has not been shown to affect summoned Servants, allowing for parameters higher and lower than those of the containers. If the hero should be utterly weak to the point of defenselessness like Stheno and Euryale, it is possible for the containers to increase their strength far beyond their regular selves.

Ascension
Under the FATE system, it is possible for Servants to undergo Ascension (霊基再臨), a reform for the Servants to become stronger by coming closer to their "starting point of conception." It may even bring about a younger, more inexperienced form without reducing their power as a Servant because it is the "most fitting figure" for them.

Form Change
Form change: Altered Morphology is an element present in Fate/Extella that allows for Servants to be strengthened in battle, altering their outward appearance and weapons.

Mythological Mystic Code
Within the Moon Cell, unlocking the human origin within a Servant grants them great power on the same scale as the Ten Crowns possessed by BB, granting them a Mythological Mystic Code (神話礼装).

Battle
Battles between Servants can be called a process of gradually shaving off the magical energy that forms their bodies. Attacks that consume a great amount of magical energy will inflict a massive amount of damage on the opponent, but it will also weaken the attacker in the process. In order to inflict a great amount of damage with minimum expenditure of magical energy, it is necessary for them to collect intelligence regarding the enemy and assault their weakness. The greatest weapon is their Noble Phantasm, and a battle between Servants can often be called a battle between Noble Phantasms.

When describing their strength, they can be likened to a single jet fighter in pure attack power, far beyond the ability for a single person to fight. While strong, they would have to refuel many times in order to destroy a city. Though there are many modern weapons that are more powerful, their status as spiritual bodies makes them among the most powerful due to being immune to modern weapons. Their Noble Phantasms can be likened to a jet's ability to load a nuclear warhead far beyond its normal fighting power, with some Servants having extremely powerful ones. With Servants, those with an "extremely average Noble Phantasm" would have one around the level of B rank which has strength able to be represented through numbers. Broken Phantasms, Invisible Air, and Gae Bolg's thrown strike all deal pure physical damage, while Gae Bolg's piercing version carries a conceptual effect able to kill opponents of a much higher level than the wielder.

True Name
The true name (真名) of a Servant is something vital to battle, as it can reveal much about them. They most often have their Masters refer to them solely by their class name unless they do not care like Assassin of Black, wish to have a closer connection to their Master like Caster after she reveals her identity, or under circumstances where it no longer matters like those trapped in the Sakura Labyrinth. There are Servants and Masters with extreme confidence or no filter in revealing their true names for all to hear, such as Rider exclaiming his name without regard and Illyasviel von Einzbern having supreme confidence in Berserker even with his name revealed.

Their names can reveal certain traits about their abilities, allowing for specific countermeasures, and there are many famous heroes that had met untimely deaths in life. Those killed by poison will be more susceptible to it, those shot down by arrows will be weak against them, those with weak spots will be severely disadvantaged if they are targeted, and those with traits like being weak to monster-slayers or dragon-slaying weapons can be specifically damaged in accordance. Even without such a specific countermeasures being available to one Master, releasing that information to the other Masters can allow for other countermeasures to be brought forth. Most Masters should know instantly of their own Servants' identities, but something like Secret of Pedigree can block even that, and the refusal of a Servant to disclose it can keep them from knowing. In the case of a weak Master susceptible to mind control, they may forgo telling them altogether until necessary.

Famous heroes like King Arthur and Siegfried are very likely to have their identities found out more easily than others, with simply glancing upon Excalibur being enough for any Heroic Spirit to identify King Arthur. Others need to utilize their Noble Phantasms before they reveal themselves, but it may require deductive reasoning even then. While the oldest legend, Gilgamesh is able to show off his Noble Phantasms without many being able to guess, and despite his believing that it should be obvious to others, generally discloses it himself. Someone like Archer, being a Counter Guardian from the future and displaying numerous Noble Phantasms with Unlimited Blade Works, is a complete anomaly to others, greatly confusing all who fight him with his contradictory traits that do not match any known hero. There are also those without specific weaknesses whose true names will bring no trouble if revealed like Astolfo.

Humans and Modern Weaponry
As spiritual beings and divine mysteries, Servants cannot be harmed by normal means and are still considered spirits even in physical form, so they cannot be physically harmed by regular humans or modern weaponry. They can only be harmed by attacks accompanied by magical energy like a Servant throwing dirks imbued with magical energy, so they can ignore even debris in battle unless it should become contaminated by an enemy's magical energy. Only Servants can normally harm other Servants physically, so even a could be used to harm a Servant should another Servant wield it. Servants that are physically incarnated through methods such as blackening can no longer return to spiritual form, allowing them to be damaged with strong enough magical weapons able to pierce the shadows surrounding them in the case of blackening.

For a human trying to apply pressure to a Servant, even one physically the size of a child, it feels like trying to bend a steel beam. Punches with all of their strength will not even cause a Servant to budge a millimeter, and even Souichirou Kuzuki, whose punch is potent enough crush a human's skull, can only slightly move Archer's head from the impact. Stabbing them with a knife does nothing but bring about a "prickling irritation" that does not hurt at all. They can by harmed by physical attacks strengthened magically through Reinforcement or enough Command Spells. "Mere bullets" normally pose no threats to Servants regardless of the caliber, but firearms wielded as regular weapons by Servants like Francis Drake's pistols are able to inflict damage, and those ascended to the rank of Noble Phantasm like through Lancelot's Knight of Honor can prove lethal with a single shot.

Other opponents
Beings other than Servants that are able to combat Servants are few in modern times. Beings such as Arcueid Brunestud at 30% of her strength, Amaterasu, and Kingprotea would always generally win against a single Servant due to their overwhelming ability. Arcueid could potentially be overwhelmed by two Servants fighting at once even though she is around four times as strong as one, while Amaterasu and Kingprotea require the strength of several Servants to be defeated. If speaking of a Servant with an extremely average Noble Phantasm, the members of the Twenty Seven Dead Apostle Ancestors, Kouma Kishima, and Aoko Aozaki can fight directly, while Ciel and the Shiki Ryougi's third personality can keep up in a defensive fight that can still be called a fight. Ryougi's normal personality and Shiki Tohno have no chance of matching Servants, but the Mystic Eyes of Death Perception they carry are capable of affecting such beings whether incarnated or spiritual bodies. Humans utilizing ten Command Spells would also be able to damage Servants. Kirei Kotomine and Kiritsugu Emiya at the peak of their strengths during the Fourth Holy Grail War could defeat Servants, but only when the weakest, Caster and Assassin, are at their most exposed, or when they have special conditions in their favor like surprise or suitability against the opponent.

Against Dead Apostle Ancestors, both are types of beings that live in Mystery, so such battles would come down to "having the means of killing the other guy somehow." Servants will generally hold a slight advantage, barring compatibility issues, and the Knight classes, Saber, Archer, and Lancer will all be able to have solid fights. While Saber's Excalibur is extremely effective against those who overwhelm by material quantity and alienness, there are those capable of surviving being hit by Excalibur-class attacks through pure endurance. At the same time, those same ones with extreme endurance would have a tough time with Lancer's Gáe Bolg. ORT, to which Earth's rules do not apply, and Primate Murder, which has an advantage against primates and requires seven Counter Guardians to control, can be called in a league of their own above both Ancestors and Servants.

Classification
Heroic Spirits summoned by the Holy Grail are placed into one of various classes. The seven standard classes are the Three Knight (三騎士) classes of Saber, Lancer, Archer, and the Four Cavalry (四騎) classes of Rider, Caster, Assassin, and Berserker. There are also non-standard Extra Classes (エクストラクラス) that can be summoned under different circumstances.

Under the Fuyuki-based rituals, it is said that only the Three Knight classes will definitely be summoned according to the framework of the ritual, allowing for variation in the rest of the classes. Classes are said to have occasionally changed between the various Fuyuki Holy Grail Wars. More than one version of the same class cannot be summoned, even if all the Masters were to use the variation in the summoning chant to get a Berserker-class Servant. Under the False Holy Grail War, the Saber-class does not even exist. Under the Moon Cell Holy Grail War, there are 128 Servants summoned at once, so there are many Servants sharing the same classes.

Servants are normally only of the singular class under which they are summoned, but certain circumstances allow for multiple classes at once or class changes. Elizabeth Bathory and Li Shuwen undergo unconventional changes to the Berserker class. Assassin Henry Jekyll and Berserker Hyde can switch between each other at will with the Noble Phantasm Dangerous Game, and Tokugawa Ieyasu can switch between all seven classes based upon his retainers with his Noble Phantasm. Double Summon allows for two classes to be utilized simultaneously, limited only to the Cavalry classes and "modern classes" like Gunner. Joan Alter displays the ability to bestow the "benefits of Berserkers" upon Servants, such as making Saber Chevalier d'Eon into "Berserk-Saber." Okada Izou possesses attributes of both the Assassin and Saber classes. While not actually changing classes, it is possible to visually alter the class of a Servant in the Moon Cell, such as Jinako Carigiri changing Karna's class from Lancer to Launcher.


 * Standard Classes


 * Saber: Servants placed within this class are agile and powerful melee warriors. It is commonly assumed to be the best class overall, with high ratings in all categories. It is one of the three Knight classes, together with Lancer and Archer and also possesses the Riding skill like the Rider class.
 * Lancer: Servants placed within this class are very agile and skilled with long-range melee weapons, such as spears, lances, etc. It is one of the three Knight classes, together with Archer and Saber.
 * Archer: Servants placed within this class are usually proficient with projectiles and can survive longer without a Master nearby, thanks to their special ability Independent Action; the strongest Archers can be difficult to control at times, in fact, due to their near-total independence from their "Masters". It is one of the three Knight classes, together with Lancer and Saber.
 * Rider: Servants placed within this class place emphasis upon speed and powerful Noble Phantasms, which often include their mounts. Their special skill is Riding, which allows them to fully utilize abilities of their mounts (which can range from simple horses to mechanical vehicles to divine or supernatural creatures.).
 * Caster: Servants placed within this class are adept in magecraft and have a special ability akin to Reality Marble, called Territory Creation, which alters or creates space around them to enhance their sorcery.
 * Assassin: Within the Fuyuki Holy Grail War, Servants placed within this class are always, as a rule, one of the 19 Hassan i Sabbah, the leaders of the clan of the Hashshashins who passed their name down. The Assassin in Fate/stay night summoned by Caster is an exception, an aberration in the system, as he was summoned by another Servant. This rule comes from how the word "assassin" itself finds its etymological roots in that clan. This rule is not present in the Moon Cell Holy Grail War and Great Holy Grail War, allowing for those known to be specialized killers to be summoned. The Assassins' special ability is Presence Concealment, which allows them to remain undetected. Offset by their stealth is their moderate combat skills. Due to this, Assassins often target Masters instead of Servants.
 * Berserker: Servants placed within this class are always heroes who have gone berserk in their lifetime. This trait allows them to use the special ability Mad Enhancement, which trades their consciousness (i.e. sanity) for a large power boost. Most Masters are incapable of controlling their Servant once Mad Enhancement has been activated, which eventually results in their death.


 * Extra Classes


 * Avenger: "Servant of Vengeance"
 * Shielder: Shielder is the "Servant of the Shield."
 * Saver: This is an irregular class in the Holy Grail War of the Moon Cell in Fate/Extra. The only case is of the class is Saver.  Saver is a "messiah" type Servant, and was carefully selected by the Automaton from the collective records of the Holy Grail War.
 * Ruler: Servants placed in this class govern the rituals utilizing the Fuyuki Holy Grail War's Greater Grail while its reserve system is in effect, such as Joan of Arc in Fate/Apocrypha. Ruler is a special Heroic Spirit summoned by the Holy Grail itself to act as the administrator of the Holy Grail War and has the ability to use Command Spells, which are normally only usable by Masters, to command the Servants.
 * Beast: This class is a special container for the Beast of 666 in Fate/Prototype.
 * Gunner is a non-standard class applicable for the Double Summon skill.
 * Alter Ego: This classification is for those created by BB as High-Servants made of several goddesses.
 * Launcher: Launcher, the "Heroic Spirit of the Laser beam", is a special nickname thought up by Jinako Carigiri for her Servant.
 * Funny Vamp (ファニーヴァンプ) is the class granted to Arcueid Brunestud by the Moon Cell should she participate as a Servant. While she takes on the Berserker class instead, Funny Vamp reflects her whimsical nature and her status as a creature that drains blood, physical energy and money from men.
 * Unclassed - Some temporary Servants, like the army summoned into Ionioi Hetairoi, are Servants without a class. Gilgamesh during Fate/Extra CCC is beyond being confined to a class, so he does not have one.
 * Gatekeeper is a Class said that Watcher could be summoned within as a Servant.
 * Others:


 * Boxer (ボクサー) is a class designated to Bazett Fraga McRemitz in the parody work Capsule Servant.
 * Butler (バトラー) is used in a joking manner in regard to Archer's household skills.
 * Gorgeous (ゴージャス) is a nickname given to Gilgamesh by Lancer.
 * Idol (アイドル) is the self-declared nickname of Lancer.
 * Manslayer (人斬り) is the self-declared nickname of Assassin.
 * Monster (モンスター): Monster is not a Servant classification, but rather the title given to the irregular being, Shiki Ryougi, who appears within the Holy Grail War of the Moon Cell.
 * Tiger (タイガー) is the name Taiga Fujimura gives herself in the Hanafuda scenario, but Illya just decides to turn it into "Taiga."

Fuyuki Holy Grail War
The events of the Fuyuki Holy Grail Wars are detailed in several stories. Some details of the Third Grail War are mentioned in Fate/hollow ataraxia. The events of the Fourth Grail War are described in Fate/Zero. The events of the Fifth Grail War are detailed in Fate/stay night and Fate/hollow ataraxia.

Moon Cell Holy Grail War
The events of the Moon Cell Holy Grail War are detailed in Fate/Extra and Fate/Extra CCC.

Great Holy Grail War
The events of the Great Holy Grail War are detailed in Fate/Apocrypha.

Servants for the canceled game Fate/Apocrypha project.

Tokyo Holy Grail War
The events of the Tokyo Holy Grail Wars are detailed in Fate/Prototype and Fate/Prototype: Fragments of Blue and Silver.

False Holy Grail War
The events of False Holy Grail War are detailed in Fate/strange fake. The Saber class is absent and replaced by the Player.

Grand Orders
The events of a number of Holy Grail Wars, Grand Orders, are detailed in Fate/Grand Order. The Protagonist has a large pool of possible Servants from which they can summon.

Chaldea summoned three Servants in the present for their experiments.
 * Chaldea Security Organization

During the war, five servants were killed by Saber Alter, and they appear as Shadow Servants. Caster was the only survivor, who teams up with the Protagonist.
 * Singularity F

Gilles de Rais manages to bring forth Joan Alter as a corrupted manifestation of Joan of Arc by using the Holy Grail. She then summons five more Servants, becoming their Master and giving them all the attribute of Berserker. While battling her, many Servants gather under the Protagonist and begin to refer to them as Master.
 * Wicked Dragon Hundred Years' War

The Protagonist teams up with Nero and a number of allies to battle a faction of Servants manipulated by Lev Reinol Flauros.
 * The Eternal Roman Empire


 * Final Blockade to the Seven Seas

Strange Tales of the Imperial Holy Grail
The events of Strange Tales of the Imperial Holy Grail are detailed in Koha-Ace.

Others

Ainsworth Holy Grail War
The events of Ainsworth Holy Grail War are detailed in Fate/kaleid liner PRISMA☆ILLYA. All Class Cards from the Fifth Holy Grail War remained until the Sixth Holy Grail War. The Assassin Class Card's Hassan-i-Sabbah changed between the two wars.

Others

 * Agrippina is mentioned to classify for the Caster class.
 * , and  are jokingly mentioned in the Fate/Prototype Drama CD as being summoned by Ayaka Sajyou to use their powers of persuasion to end the Second Holy Grail War without any casualties.
 * Armstrong (アームストロング) is a Servant mentioned by Shinji Matou to be a participant in the Moon Cell Holy Grail War, possibly referring to the American astronaut or the famous engineer.
 * Bucephalus, Mithrenes, and the soldiers of Ionioi Hetairoi are all temporary Servants summoned and sustained by the Reality Marble.
 * Charles VII is mentioned to classify for the Berserker class.
 * Dragon Rider (ドラゴンライダー) - The development stage of Fate/Zero was to feature a Rider who rode a dragon and had a climactic battle with Saber that ended with her using Excalibur, but Nasu could not think of one who rode a minor dragon. Alexander the Great was originally to be an unspecified, abnormal-class Servant, but Gen Urobuchi wished for him to be Rider instead and ultimately replaced the idea. Caster and his Gigantic Horror were later used to fill the place of facing Excalibur.
 * Edward, the Black Prince is mentioned to classify for the Saber and Archer classes.
 * and of the Shinsengumi can be summoned using Sakura Saber's Flag of Sincerity.
 * Nebuchadnezzar II is mentioned as the proper owner of the Hanging Gardens of Babylon as a Noble Phantasm.
 * Peter the Cruel is mentioned to classify for the Caster class.
 * Qin Shi Huang is planned to be summoned as a Servant in Fate/strange fake.
 * Scathach,, the , , and are potential Servants that can be summoned by the Player.
 * Scipio is mentioned to classify for the Rider class.
 * Sun Wukong briefly appears in Koha-Ace.
 * was to be the Rider-class Servant of Old Fate, but was replaced by Perseus for Fate/Prototype.
 * - Urobuchi considered using one of the Chinese Xian when attempting to think of the Caster-class Servant for the Fourth Holy Grail War that eventually ended up being Gilles de Rais. Nasu explained the Western-only rule of the Fuyuki system, and felt that the Xian would be too strong.
 * Numerous other Joke Servants were designed for a contest feature in the parody 4 Koma manga Fate/school life.

Servant Parameter listing
Parameters for each Servant