Hassan of the Hundred Faces, Class Name Assassin, is the Assassin-class Servant of Kirei Kotomine in the Fourth Holy Grail War of Fate/Zero, and one of the Servants summoned by Ritsuka Fujimaru of the Grand Order conflicts of Fate/Grand Order. He is unique in that he has the capability to manifest as multiple entities at once. The multiple bodies of Assassin can vary widely in age, gender, build, and style of dress, but in general, their hair appears purple, and their skin and clothing are nearly black. They wear the standard skull mask associated with the known Hassan of the other Grail Wars. The masks change as he changes personalities. Each of the Assassins has their own personality, and their experiences are not shared between them. The female Assassin is shown to be the main one to interact with Kirei. Assassin's goal in wanting to obtain the Grail is "to have a perfect and unified personality." Due to his Master having no intention of winning the war, he is instead damned to the fate of a voyeur. Kirei following the orders of Tokiomi makes it so he is truly a servant of a servant. He had plotted to hijack the Holy Grail before either Kirei or Tokiomi in the event the War had gone in their favor, but he didn't even get a chance to display his rebellious side before becoming the first Servant eliminated from the war.