Which Assassin's Creed game was the first main entry to feature a female protagonist, Evie Frye, as a playable character?

Assassin's Creed Syndicate was the first main entry to feature Evie Frye as a playable female protagonist.

Released in 2015, Syndicate follows twins Jacob and Evie Frye in Victorian London. Evie is not a brief supporting character: she is playable throughout the campaign and has story missions that emphasize stealth, investigation, and the search for an ancient artifact.

Earlier Assassin's Creed releases had already featured playable female Assassins in other forms. Aveline de Grandpré is the protagonist of Assassin's Creed III: Liberation, a standalone title originally released for PlayStation Vita. Female characters also appear in multiplayer, expansions, and later main entries. The distinction here is the first main numbered-style entry to make a woman one of its principal playable heroes.

Odyssey later lets players choose Kassandra, and Origins features Aya in selected sequences, but neither changes Syndicate's place in this specific milestone.