Kassandra is the canon protagonist of Assassin's Creed Odyssey.
Odyssey lets the player choose Kassandra or Alexios as the playable mercenary. Ubisoft's official story material identifies Kassandra as the canon character, while Alexios appears in the narrative as Deimos, a major opposing figure. Both choices use much of the same branching story structure, which is why the two names are often treated as interchangeable by players.
Kassandra is a descendant of the Spartan king Leonidas I and travels through the Greek world during the Peloponnesian War. The game is set in the fifth century BCE, long before the events of most earlier Assassin's Creed titles. Phoibe and Aspasia are important characters, but neither is the selectable protagonist.