Which game completes Ezio Auditore's main trilogy in Assassin's Creed?

Assassin's Creed: Revelations completes Ezio Auditore's main trilogy.

Released in 2011, Revelations follows the older Ezio as he travels to Constantinople, the capital of the Byzantine Empire. He searches for keys connected to Altaïr's former stronghold in Masyaf and uncovers information linking the lives of both protagonists.

The game is the third major title centered on Ezio, following Assassin's Creed II and Assassin's Creed: Brotherhood. It also includes playable sequences featuring Altaïr, giving the original protagonist a concluding chapter while Ezio's story reaches its own resolution.

Assassin's Creed III follows Revelations and shifts to a new central protagonist, Ratonhnhaké:ton, commonly called Connor. The term “trilogy” refers to Ezio's three main appearances, not to every title released during that period; several spin-offs were also published.