Altaïr Ibn-La'Ahad is a Master Assassin at the start of the first Assassin's Creed game.
In the 2007 game, Altaïr holds the senior rank of Master Assassin and leads missions for the Levantine Brotherhood during the Third Crusade. His reckless failure during the opening operation causes him to lose his rank and equipment.
Mentor Al Mualim demotes Altaïr to the rank of Assassin and sends him on a series of missions to restore his standing. These assignments take him through Jerusalem, Acre, and Damascus while he investigates targets connected to the Templars.
Players sometimes remember Altaïr chiefly as a novice because much of the early game depicts him rebuilding his reputation. That is a consequence of the opening punishment, not his original status. Later in the story, Altaïr becomes Mentor and reforms the Brotherhood.