Ezio Auditore is the Assassin known as Mentor who leads the Brotherhood in Renaissance Italy.
Ezio is the central character of Assassin's Creed II, Assassin's Creed: Brotherhood, and Assassin's Creed Revelations. He begins as a young Florentine nobleman and gradually becomes an Assassin after the execution of members of his family. His pursuit of the people responsible develops into a long campaign against Templar influence in Italy and beyond.
In Brotherhood, Ezio rebuilds the Assassin presence in Rome and takes the title of Mentor. His leadership involves training recruits, coordinating missions, and confronting the Borgia regime. Later, Revelations follows him to Constantinople and links his story to Altaïr through the Masyaf library.
Altaïr is the earlier Syrian Assassin, Connor is the protagonist of the American Revolution storyline, and Arno is the lead character in Unity. All are major Assassins, but only Ezio matches this Renaissance Italian leadership description.