In Assassin's Creed II, which Borgia leader is the game's main historical antagonist?

In Assassin's Creed II, Rodrigo Borgia is the main historical antagonist opposing Ezio Auditore.

Rodrigo Borgia appears in the game as the powerful Templar leader behind a broad political conspiracy. Historically, Rodrigo was a member of the influential Borgia family and became Pope Alexander VI in 1492. The game uses that historical identity while incorporating the fictional conflict between the Assassins and Templars.

Ezio eventually confronts Rodrigo in the Vatican during the game's climax. Rodrigo possesses the Apple of Eden and seeks access to the Vault, believing that the artifact and prophecy will grant him extraordinary power. His plans connect the fictional storyline to the game's Renaissance setting.

Cesare Borgia, Rodrigo's son, becomes the principal human antagonist in Assassin's Creed: Brotherhood, which is why the two characters are often confused. Rodrigo's papal title and political influence make him the central Borgia threat in Assassin's Creed II.