Which Assassin's Creed game introduced the modern Animus user Desmond Miles?

The first Assassin's Creed game introduced the modern Animus user Desmond Miles.

Desmond is a descendant of several historical Assassins, including Altaïr Ibn-La'Ahad. Abducted by the fictional company Abstergo Industries, he is placed in the Animus, a machine that allows a person to relive ancestral memories encoded through genetic memory.

Although Altaïr is the main historical playable character, Desmond provides the modern storyline and frames the historical sequences. His sections reveal that Abstergo is connected to the modern Templars and that the Animus is being used for more than entertainment or research.

Desmond remains a central modern protagonist through Assassin's Creed II, Brotherhood, Revelations, and Assassin's Creed III. Later games change the modern-player structure and introduce new contemporary characters, so Desmond's first appearance belongs specifically to the 2007 original.