In Assassin's Creed, Al Mualim is Altaïr's mentor and the leader of the Assassins in Masyaf.
Al Mualim, whose name means “the Teacher,” directs the Brotherhood from its mountain stronghold in Syria. After Altaïr violates the Assassin's three central tenets during a failed mission, Al Mualim strips him of rank and equipment before assigning missions intended to restore his status.
The targets given to Altaïr are connected to the Templar cause during the Third Crusade. Al Mualim appears to be guiding Altaïr toward discipline and understanding, but the story later reveals a deeper personal and political motive.
He should not be confused with Altaïr's fellow Assassin Abbas Sofian or with the game's Templar targets. Al Mualim's role is especially important because he links the Brotherhood's teachings, the Apple of Eden, and the game's final revelation.