Servant

Servants (サーヴァント) are Heroic 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 that are bound to the Master. Pure Heroic Spirits can only be summoned by the World, and summoning even one is considered to be a miraculous occurrence. Even the Holy Grail lacks the power to summon a true Heroic Spirit, so the process is facilitated by summoning the into one of seven vessels prepared beforehand. These vessels, classes, are classified based on their primary roles. Heroic Spirits can be summoned into any "class" that reflects the abilities they had in life. While they generally appear as they were in their prime, those with some kind of curse or strong attachment to their appearance can even be summoned in the form they had just before death.

Although too powerful to be controlled by humans, the prospect of having a wish granted by the Holy Grail serves as incentive cooperate with a Master. There are also those like Lancer who lack an actual wish, instead simply wishing to battle other heroes freely. They also require their master as an anchor to the world, so killing their Master would go against their purpose. Masters also possess three Command Spells with which to force a Servant to obey their orders.

The Servant system was designed to summon only the souls of "true" heroes - benevolent, honorable, and selfless protectors of humanity and justice. Due to the corruption of the Holy Grail in the third Holy Grail War, evil spirits can be summoned. These entities can still be considered to be Heroic Spirits if they were widely worshipped, respected, or feared in life.

Spiritual body
“Spiritual Body” is a word that describes an existence with spiritual properties. In other words, a shape is constructed without relying on components with physical properties. On the other hand, “Material Body” means something that is identical in structure as our flesh bodies. A Material Body, just like us, cannot walk through walls, and will hurt and become wounded when beaten with an iron baton. However, a Spirit Body is capable of completely disregarding such physical interference. Attacking a Spiritual Body with a baton or sword (unless they are magical items) will only hit empty space.

When Servants materialise, they acquire Material Bodies in this world. They can also switch to Spiritual Bodies through their will. Spiritual Bodies have the advantages such as low mana consumption, and difficult to be detected by enemies. One of the properties of a Spiritual Body is that it is unaffected by physical interference, but conversely it is difficult for a Spiritual Body to affect a Material Body. As a result, Servants Materialise when engaging in combat.

Although both are Material Bodies, the composition of Servants and Humans are drastically different. Naturally, it is impossible to transplant a portion of a Servant’s Material Body to a human. However, Shirou Emiya was able to successfully transplant Archer’s left arm to replace his own lost left arm. How is this possible? It is because Shirou and Archer – Heroic Spirit Emiya are the same person.

Servants can revert to spirit form when not in battle at will, to reduce the burden on their Masters. In this form they can pass through inorganic substances that aren't dense with mana; they are also invisible to the naked eye (except for the Master they connected with) and most forms of scrying in this state, facilitating the concealment of their identity. When Lancer invaded the Emiya mansion, he used his spirit form to infiltrate the house. He subsequently reverted to physical form to drop from the ceiling into the living room. They cannot be affected by normal interference when dematerialized, but need to materialize for battle. As Human Spirits are they able 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.

When a Heroic Spirit emerges into this world, he first acquires a Spiritual Core. The Heroic Spirit then materialises as the body envelopes this Spiritual Core. In order to defeat a Heroic Spirit, one must inflict damage to the Spiritual Core. The Spiritual Core gradually diminishes as a result of massive magical energy expenditure or sustaining bodily damage. Under these adverse conditions, the Heroic Spirit’s expenditure of magical energy will escalate, and should damaged be inflicted through powerful magical energy, curse, or Noble Phantasm, the Spiritual Core will be destroyed, and the Heroic Spirit will no long be able to remain materialised. The heart and head are connected directly to the Spiritual Core, thus they are the weaknesses of Heroic Spirits. Sustaining damage at these locations will significantly weaken the Spiritual Core.

Summoning
There are several factors that determine which Heroic Spirit the Master will summon. Performing a summoning ritual to interfere with the Greater Grail causes it to borrow the information of the main body of the Greater Grail in the Throne of Heroes. The information, the soul of highest purity of the Heroic Spirit, is taken into the container of the Class and becomes a created "copy", so to speak, of the Heroic Spirit, a Servant.

It is possible for the Grail to simply select a Servant for the Master by choosing a Heroic Spirit with good affinity with them, but they can also designate the Heroic Spirit during the summoning ritual by preparing a catalyst with ties to the Servant that they desire. If they choose a catalyst for multiple Heroic Spirits like the, the symbol of the , the Heroic Spirit among the candidates that has good affinity with the Master will be chosen. The magus must choose whether to go for good compatibility, possibly loosing the gamble with a poor Servant, or to draw a specific Servant of their choice with a catalyst and possibly be ruined by bad compatibility.

While the rituals are generally specific, their main goal 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 prana through normal methods. The Grail of Fuyuki requires seven Servants, so it will pick from anyone appropriate until it has all seven in cases where more capable magi have not summoned Servants already.

Examples of catalysts include:
 * King Arthur: Avalon, the sheath of Excalibur.
 * Heracles: The Axe-sword, a slab of rock from a temple of Heracles.
 * EMIYA: Rin's Pendant
 * Medusa: Mirror dug up from a temple in Eritrea, an item with ties to an old Earth goddess of Greece.
 * Medea: Literature from Colchis with ties to Medea.
 * Sasaki Kojiro : The mountain gate.
 * Hassan-i-Sabbah: Since Hassan is the origin of the word Assassin, the class of Assassin itself is Hassan's catalyst.
 * Cú Chulainn: Jewel on which is engraved an original rune inscribed by Cu Chulainn that had been crafted into earrings.
 * Alexander the Great: Shard of cloth from his mantle.
 * Gilgamesh: The first snake's Shed Skin.
 * Siegfried: Bloodstained leaf of a Sacred Fig tree.
 * Astolfo - Glass bottle which had a liquid stain left on it.
 * Chiron - Ancient arrow blackened by blood.
 * Frankenstein - The blueprints of the 'Ideal Human.'
 * Remnant of the : Heracles,, Medea, , or other crew members
 * Splinter of the - King Arthur, Lancelot,, Gawain, , , Mordred, or other members of the Round Table.

When summoned, Servants are imparted with knowledge of technology, culture, science, and terms of the era they were summoned into, as well as skill in languages. 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. This is largely to prevent Servants from periods significantly before the era of a Grail War in question from suffering crippling culture shock which would otherwise prevent them from fulfilling their duties, and also enable them to blend in with that era's society. It is not all-encompassing, so concepts may have to still be explained to them. Saber does not understand the idea of dating until it is framed into the similar method of courting of her time.

Without such knowledge, a Servant's potential would be crippled. This knowledge does not just cover history but all aspects of "modern" life during the Grail War in question, to the point that Servants can find things that would have been unthinkable in their lifetimes to be mundane or even worthy of scorn. They are not granted knowledge on other Heroes through the Grail, but rather from knowledge gain within the Throne of Heroes. Saber, not being a proper Heroic Spirit, is able to identify those who are older like Cú Chulainn, but cannot identify the legends of newer Heroic Spirits like Gilles de Rais even after being told of him.

Irisviel von Einzbern figured that Saber would be surprised upon flying in a plane, but she does not have much of an opinion after receiving knowledge of it and the possible ability to fly one with her Riding. While not given enough information to actually drive vehicles, her ability is able to manage such through intuition even if she does not actually recognize what each separate control of a vehicle will actually perform what action. Rider does note surprise at the knowledge of the true state of the world being a sphere, and he has enough familiarity to use modern money, order a specialty t-shirt through the postal service, and buy and play a video games console.

Battle
Battles between Servants can be called a process of gradually shaving off the magical energy that forms the 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.

The true name of a Servant is something vital to battle, as it can reveal much about them. It 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, and those with weak spots will be severely disadvantaged. There are also things like the traits of a dragon being weak against dragon-slaying weapons, and even without such a specific countermeasure, releasing that information to the other Masters can allow for other countermeasures.

Famous heroes like King Arthur and Siegfried are very likely to have their identities found out more easily than others. Simply glancing upon Excalibur is enough for any Heroic Spirit to know her name, while someone like Gilgamesh is able to show off his Noble Phantasms without many being able to guess. Others need to utilize their Noble Phantasms before they reveal themselves, but it may require deductive reasoning even then. There are those without specific weaknesses whose true names will bring no trouble if revealed like Astolfo.

Their strength can be likened to the attack power of one "fighter", too overpowering for a single person to stand against. It would still take them many times to refuel in order to destroy a city. Their main strength is their inability to be harmed by regular weapons, meaning that even though there are numerous destructive modern weapons, Servants are among the most powerful. Just as a fighter can load a nuclear warhead, each Servant has the own Noble Phantams, and the ones with ridiculously powerful ones are the main reason for likening them to a fighter.

Beings other than Servant able to combat Servants are few in modern times. Matched up against Servants with extremely average Noble Phantasms, those of B rank with the ability being represented by numbers, Arcueid Brunestud would always generally win against a single Servant due to her overwhelming strength, but would likely fall if two were to fight her at once. 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. Humans utilizing ten Command Spells would also be able to damage Servants.

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 Gae Bolg. ORT, to which Earth's rules don't apply, and Primate Murder can be called in a league of their own above both Ancestors and Servants.

Classification
Heroic Spirits summoned by the Holy Grail are place into one of seven categories. The seven standard classes are Saber, Lancer, Archer, Rider, Caster, Assassin, and Berserker. According to Rin, servant classes are changed between each war, so other classes, such as Avenger created by the Einzberns in the Third Holy Grail War, can also be summoned. The Three Knight classes are the only Servants who will definitely be summoned according to the framework of the Holy Grail War, allowing for variation in the rest of the classes. 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.
 * 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: 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 (although this rule does not hold absolutely true in the Fate/Extra reality). 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. The Assassins' special ability is Presence Concealment, which allows them to remain undetected. Offset by their stealth is their weak 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.
 * Avenger: It is not one of the seven normal classes, and it has only been used once as a unique container for Angra Mainyu in the Third Holy Grail War.
 * 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.
 * Funny Vamp: 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.
 * Ruler: Servants placed in this class govern the Holy Grail War of Fate/Apocrypha. Joan of Arc is placed in this class. Under the special Ruler class, she 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 666th Beast in Fate/Prototype.
 * Monster: 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.

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. Heroic Spirits are not affected when summoned, so they may have statistics higher or lower than those of the class container.

Holy Grail War

 * For more detail about Fuyuki's Holy Grail War, see Holy Grail War.

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.

Even though the setting is in Japan, there are so few Japanese Heroic Spirits summoned in the Fuyuki Holy Grail even if they have geographical boost advantage because the Holy Grail is a western Christian concept.

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

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

Servants for the canceled game Fate/Apocrypha project.

Fate/Prototype
The events of the Grail War of Fukutoshin are detailed in Fate/Prototype.

Fate/strange fake
The events of the Grail War of Snowfield are detailed in Fate/strange fake.