Which Italian polymath appears as an ally in Assassin's Creed II?

Leonardo da Vinci appears as an ally in Assassin's Creed II.

In the game, Leonardo is a friend of Ezio Auditore and uses his technical knowledge to decode pages of Altaïr's Codex. He also repairs and improves equipment for Ezio, including the hidden blade, and helps the protagonist understand inventions that advance the story.

The historical Leonardo da Vinci was a painter, engineer, anatomist, and inventor associated with the Italian Renaissance. Assassin's Creed II uses his documented connection to figures such as Lorenzo de' Medici as a foundation, then places him inside the series' fictional Assassin and Templar narrative.

Leonardo's role is not the same as that of Ezio's mentor. That role is primarily associated with Mario Auditore and other members of the Assassin network. Leonardo also appears in Assassin's Creed: Brotherhood, where the game expands its fictional version of his engineering work.