What is the name of the second mainline Assassin's Creed game?

The second mainline Assassin's Creed game is Assassin's Creed II. Ubisoft released it in 2009 as the direct successor to the 2007 original.

The game shifts its historical focus from the Crusades to Renaissance Italy and introduces Ezio Auditore da Firenze. Its story follows Ezio's transformation from a Florentine nobleman into an Assassin while he encounters figures and locations associated with the period, including Leonardo da Vinci, Florence, Venice, and the Vatican.

Assassin's Creed II is sometimes confused with Brotherhood because the latter continues Ezio's story and was released soon afterward. Brotherhood is a separate sequel, while Revelations completes Ezio's trilogy. The game's success also led to related titles such as Assassin's Creed II: Discovery and the standalone multiplayer-focused companion Assassin's Creed: Project Legacy.