Desmond Miles is the main present-day protagonist of the first Assassin’s Creed.
In the modern-day sections, Desmond is abducted by Abstergo Industries and forced to use the Animus, a machine that lets him experience ancestral memories. The first game primarily presents Altaïr’s medieval adventures through Desmond’s perspective and frames the historical conflict within a contemporary conspiracy.
Desmond is a descendant of several important Assassin figures, including Altaïr, Ezio, and Ratonhnhaké:ton. His genetic memories make him valuable to Abstergo, whose researchers seek information connected to the First Civilization and the Assassins’ past.
William Miles is Desmond’s father and an important later character, but he is not the first game’s present-day protagonist. Warren Vidic is an Abstergo scientist, while Clay Kaczmarek is another modern-day subject associated with the Animus program.