Al Mualim is the Assassin Brotherhood leader Altaïr meets in Masyaf in the original Assassin's Creed.
Al Mualim, whose title means “the Teacher,” leads the Assassins from their fortress at Masyaf during the game's Third Crusade setting. After Altaïr breaks the Brotherhood's code, Al Mualim strips him of rank and sends him on missions to regain his status. These targets connect Altaïr to the political conflict in the Levant.
The character is presented as the mentor and master of the Masyaf Assassins, but the story later reveals that his relationship with Altaïr is more complicated than a simple teacher-student bond. Masyaf itself is a real Syrian fortress associated historically with the Nizari Ismaili state.
Al Mualim is sometimes confused with Rashid ad-Din Sinan, the historical leader commonly associated with the Assassins in Syria. The game draws on that history but uses Al Mualim as its fictionalized character name.