Kephallonia is Kassandra's childhood home in Assassin's Creed Odyssey.
The game opens on Kephallonia, an island in the Ionian Sea, where Kassandra works as a mercenary. The island introduces the game's dialogue system, exploration, combat, and naval mechanics before the story expands across the Greek world. It also establishes important details about Kassandra's family and the events that separate her from her home.
The name is the modern form commonly used for Cephalonia, and the game presents the island within its historical setting during the Peloponnesian War. From Kephallonia, the protagonist travels to places including Megaris, Phokis, Athens, Sparta, and numerous Aegean islands.
Kephallonia should not be confused with Naxos or Delos, which are separate Greek islands visited or referenced during the wider adventure. Odyssey allows players to choose between Kassandra and Alexios, but the opening island remains Kephallonia regardless of that selection.