Kassandra is the canon playable character according to the Assassin's Creed Odyssey novel.
Odyssey lets the player choose Kassandra or Alexios as the game's controllable protagonist. The official tie-in novel by Gordon Doherty uses Kassandra, establishing her as the canonical version for the game's narrative continuity.
Both characters can appear in the game, but the selected protagonist becomes the Eagle Bearer, while the other takes the role of Deimos. This flexible design means players may encounter different character presentations in their own playthroughs.
Kassandra's story is set in ancient Greece during the Peloponnesian War. She is a descendant of Leonidas I through her family line and later appears in Assassin's Creed Valhalla's modern-day storyline, extending her role beyond Odyssey.