Which Assassin's Creed title was the first to feature a playable female protagonist, Aveline de Grandpré?

Assassin's Creed III: Liberation was the first Assassin's Creed title to feature a playable female protagonist, Aveline de Grandpré.

Liberation was released for PlayStation Vita in 2012 and is set in eighteenth-century Louisiana. Aveline is a French-African Assassin from New Orleans who becomes involved in the political and economic conflicts surrounding the end of French colonial rule and the rise of Spanish influence.

The game gives Aveline three disguises, each supporting different abilities and social access. Her Assassin persona is suited to combat and climbing, her Lady persona enables social manipulation, and her Slave persona helps her move through certain environments inconspicuously.

Later games also feature women as playable leads or major playable characters, including Evie Frye in Syndicate and Kassandra in Odyssey. Those later appearances do not change Liberation's place as the first title built around Aveline as its central playable protagonist.