Labib

Labib was the fighting instructor of Altaïr and Abbas when they were younger.

Characteristics and personality
Labib seemed to be a combat-loving, oblivious person, as when Altaïr and Abbas started to fight - after Abbas knew that his father had killed himself - the instructor almost let Abbas spar Altaïr to death in a rage fit - not even stopping the fight after the furious apprentice drew blood.

Trivia

 * Labib was only mentioned in a flashback of Assassin's Creed: The Secret Crusade.

Source
Assassin's Creed: The Secret Crusade