In the original Assassin's Creed, what is the name of the Assassin protagonist set in 1191?

The original Assassin's Creed follows Altaïr Ibn-La'Ahad as its Assassin protagonist in 1191.

Altaïr is introduced as a highly ranked member of the Levantine Assassin Brotherhood. After failing an important mission, he is demoted by his mentor, Al Mualim, and must regain his status by carrying out a series of investigations and assassinations.

The game takes place during the Third Crusade, visiting cities including Masyaf, Jerusalem, Acre, and Damascus. Altaïr's targets and the political motives behind the killings gradually expose the conflict between the Assassins and Templars.

Altaïr is sometimes confused with Ezio Auditore, the central character of the next major historical storyline. Ezio stars in Assassin's Creed II, Brotherhood, and Revelations, whereas Altaïr's later life is explored in Assassin's Creed Revelations.