Hassan-i-Sabbah is the title given to the Leaders of the Hashashin order. They are all Assassin-class.
There are 19 Hassan-i-Sabbah in total. Only 4 made an appearance in Fate/Grand Order.
- Cursed Arm Hassan, 2★ from the original Fate/stay night, Heaven's Feel Route.
- Hundred-Faced Hassan, 3★ from Fate/Zero.
- Hassan of Serenity, 3★ from Fate/Prototype : Fragments of Blue and Silver.
- Hassan (Enemy), an type of Enemy that appeared in the Fate/Accel Zero Order Event and in Camelot. Comes in 3 variants.
- King Hassan, 5★ from Fate/Grand Order.