Kassandra is the canonical Eagle Bearer in Assassin’s Creed Odyssey.
Assassin’s Creed Odyssey lets players choose between Kassandra and Alexios as the playable character. However, the official tie-in novel uses Kassandra as the protagonist, establishing her as the canonical Eagle Bearer for the wider story. In the game itself, the selected character can still determine how the player experiences the campaign.
The Eagle Bearer is a mercenary descended from the Spartan king Leonidas I. The story takes place during the Peloponnesian War in the fifth century BCE, with locations across ancient Greece and the Aegean world. The protagonist carries Leonidas’s broken spear, which has supernatural properties and links the narrative to the Isu mythology of the series.
A common misunderstanding is that choosing Alexios makes Kassandra non-playable. Both characters can be selected in the game, but the canonical version used by the novel and later continuity is Kassandra. Odyssey was released in 2018.