Which Assassin's Creed protagonist is an ancestor of Desmond Miles and fights during the Third Crusade?

Altaïr Ibn-La'Ahad is the Assassin's Creed protagonist who is Desmond Miles's ancestor and fights during the Third Crusade.

Altaïr is the central historical character in the first Assassin's Creed game. He is a Syrian-born member of the Assassin Brotherhood whose missions take place mainly in the Levant in 1191. The game visits Jerusalem, Acre, and Damascus while Altaïr investigates a network of political targets connected to the Templars.

Desmond relives Altaïr's genetic memories using the Animus. This creates the franchise's defining link between a modern protagonist and historical ancestors. Altaïr's experiences also influence the Brotherhood's methods and philosophy across later stories.

The name is sometimes written without the diacritic as Altair, but “Altaïr Ibn-La'Ahad” is the character's commonly used full form. He should not be confused with Ezio Auditore, another major Assassin and Desmond ancestor whose story occurs centuries later in Renaissance Italy.