Grigori Rasputin, Class Name Alter Ego (アルターエゴ), is an Alter Ego-class Servant working as one of the three Alter Ego apostles of the Alien God in the Lostbelts of Fate/Grand Order: Cosmos in the Lostbelt. They are working in tangent with the seven Crypters attempting to supplant the Greater History of Man with the Lostbelts. He first appears under the name Kirei Kotomine (言峰 綺礼, Kotomine Kirei), acting as an a Executor from the Church tasked with overseeing the investigation into the dissolution of the previous staff of Chaldea for the incoming director Goldolf Musik.

The monster responsible in part for the Romanov Dynasty's collapse, Grigori Rasputin was a self-proclaimed holy man who earned the trust of Tsar Nicholas II's family by his miraculous healing of the tsar's son Alexei, who suffered from hemophilia. He used the favor this earned him to enrich himself and became an influential part of the tsar's court. Rumors spread that he was engaged in heresy and had been carrying on an adulterous affair with the tsarina, but despite the protests of prime minister Pyotr Stolypin and the tsar's secret police the tsar took no action against him. Following further allegations of rape made against him and a string of Russian defeats in World War I, Rasputin was assassinated by a group of nobles who blamed his influence over the tsarina for Russia's decline.

(Source: TYPE-MOON Wiki)