Assassin

Assassin is one of the seven normal Servant classes summoned for the Holy Grail War. Servants placed within this class are always, as a rule, one of the 19, the leaders of the clan of the s who passed the name down. This rule comes from how the word "assassin" itself finds its etymological roots in that clan.

The original Grail system didn't allow the summoning of evil Heroic Spirits (this rule was jeopardized when the Grail became corrupted), and a real, perfect assassin should normally be one nobody knows (thus one who cannot be a Heroic Spirit). For those reasons, the only Heroic Spirits normally allowed in that class are those leaders. The Assassin in Fate/stay night summoned by Caster is an exception, an aberration in the system, as he was summoned by another Servant.

The Assassins' special ability is Presence Concealment, which allows them to remain undetected. This, and their weak fighting skills, makes the Assassin class rely heavily on stealth and usually go after human Masters rather their Servants.

Known Assassins

 * The Assassin summoned by Caster in Fate/stay night claims to be, even though he admits this identity is fake.
 * True Assassin serving Matou Zouken in Fate/stay night is an incarnation of one of.
 * Assassin serving Kotomine Kirei in Fate/Zero is another Hassan-i-Sabbah, also known as The Hundred-Faced Hassan.
 * Another Assassin makes a quick appearance in Fate/hollow ataraxia.