In Assassin's Creed, what is the name of Altaïr's mentor in Masyaf?

Al Mualim is Altaïr's mentor in Masyaf in the original Assassin's Creed.

Al Mualim leads the Assassin Order from its mountain stronghold at Masyaf during the Third Crusade. After Altaïr breaks the Order's rules during an early mission, Al Mualim demotes him and assigns a sequence of targets. These missions take Altaïr to major cities in the Holy Land.

The name is an honorific meaning “the teacher” or “the master,” rather than a modern personal name. The character initially appears as the leader who guides Altaïr, but the game's central mystery gradually reveals that his motives are more complicated than they first seem.

Robert de Sablé is a Templar Grand Master and one of Altaïr's targets. Abbas Sofian belongs to later stories connected with the Assassin Order. William of Montferrat is another target. None of those characters is Altaïr's mentor, making Al Mualim the specific answer for Masyaf's leader.