Which Assassin's Creed game was the first main entry to feature a female protagonist option?

Assassin's Creed Odyssey was the first main entry to feature a female protagonist option.

Odyssey lets the player choose Kassandra or Alexios as the playable misthios. Kassandra is the female protagonist, while Alexios is the male option; the selected character leads the story and the unselected sibling remains part of the narrative. This choice made Odyssey distinct from earlier main entries, whose central playable characters were presented as fixed protagonists.

Assassin's Creed III: Liberation had already featured Aveline de Grandpré as a female playable Assassin, and several earlier games included female playable characters in side roles, multiplayer, or shorter sections. However, Odyssey was the first mainline game to offer a choice between a female and male protagonist for the full central campaign. Unity included Elise as an important character but did not make her the playable protagonist.

Odyssey launched in 2018 and is set in ancient Greece during the Peloponnesian War. Kassandra is also the canon protagonist in later series material, although the game allows players to choose either sibling.