Gilgamesh (ギルガメッシュ, Girugamesshu?) is an enigmatic Archer-class Servant. He appears familiar with Fuyuki City and claims to have a past relationship with Saber. Typically clad in an ornate golden armor, he possesses an immense number of Noble Phantasms, though none are representative of his true identity.
Like Saber, he participated in the 4th Holy Grail War during the events of Fate/zero with his true identity unrevealed at that time. But while Saber was summoned a second time for the 5th Holy Grail War in Fate/stay night, he stayed in this world since the end of the previous war.
As his name suggests, Gilgamesh is the great half-god, half-human king that ruled the Sumerian city-state of Uruk, the capital city of ancient Mesopotamia, in the years before Christ. He was an ultimate, transcendent being so divine as to be two thirds god and one third human, and no others in the world could match him. He was a despot possessing high divinity who believed he was invincible. He is not merely a legend, and is said to have actually existed and ruled during the Sumer Dynasty five thousand years ago. He was the King of Heroes who possessed all things in the world, whose tale is recorded in mankind's oldest epic poem, the "Epic of Gilgamesh."