Which Assassin's Creed game introduced the modern-day character Desmond Miles?

The original Assassin's Creed game introduced the modern-day character Desmond Miles.

Desmond is a former Assassin descendant captured by Abstergo Industries, a fictional corporation linked to the Templars. Through the Animus, he relives memories inherited from his ancestor Altaïr Ibn-La'Ahad. This modern-day framework connects the game's medieval missions to a continuing conflict that extends across the series.

Desmond also appears in Assassin's Creed II, Brotherhood, and Revelations, which can make the first appearance easy to misplace. The original game was released in 2007 and established the series' central contrast between historical memory and contemporary events. Altaïr's story takes place during the Third Crusade, while Desmond's sections occur in a modern laboratory operated by Abstergo.