I'll be collecting here the info known about former Dorm Heads. Those who already got their own page by virtue of having a FC will have their info taken to said page.
Irillis von Einzbern: Described as a female clone of Acht, a very dignified person. She was apparently very unfit for combat and was described as being weaker than the Player Characters, and is mentioned as the weakest Dorm Head in the history of OLYMPUS. It is known that her Servant was a Saber-class Lancelot, and that they were defeated by Mori Kaoru. Irillis died on Lancelot's arms.
Hubris: The first Dorm Head of Midle-East. Had a Marauder-class Hannibal. His own advisor, Gluttony, who had a Caster-class Scherezade, rebelled against him, and both died in the ensuing duel.
Wrath: The second Dorm Head of Middle-East. Died during the Half-Blood Outbreak.
Sea of Estray:
Queen: No info is known, except that she died.
Stephen Stockholm: No info is known, except that he died.
Apparently, the Sea of Estray dorms have always been very conflicted, and neither of the former Dorm Heads were very suited for the task.
Celestina: First Dorm Head of the Dead Apostles dorm. Was tricked by Jacques into fighting Illerina, and she pushed a weird button that made the homunculus go crazy on her. Illerina destroyed both her and her Servant, a Saber-class Hervor.
Altair Al-Liever: An Atlas Dorm Head that rebelled against OLYMPUS along with rogue groups of Middle-Eastern magi, in the incident known as Desert Skies. It did not end well. A relative of the Vega Al-Liever that appears in Moon White.
Fujou Kurotsuchi: See her page.
Asakami Ayame: The first Dorm Head of the Asakami Clan. Used to be considered the greatest Pyrokinetic alive. Literally burned herself out with her own powers to save someone.
Tao Zhen: See her page.
???: Lost in a battle against Jacques and fell from OLYMPUS in the fight.
We have very little data about the former HB Dorm Head, and no data at all about former Dorm Heads of: 8th Sacrament, Ryougi Clan and Taima.