In Assassin's Creed Odyssey, the secret organization influencing ancient Greece is the Cult of Kosmos.
The Cult of Kosmos is a network of powerful figures operating throughout the Greek world during the Peloponnesian War. Its members manipulate political events, military conflicts, and public life while pursuing their own vision of order. The player investigates the cult, identifies its members, and confronts its leadership through a major branch of the story.
The organization is represented by a branching clue system rather than being revealed all at once. Each cultist is connected to evidence, regions, and other members, so exploration and investigation gradually uncover the wider conspiracy.
The Cult of Kosmos belongs specifically to Odyssey's ancient Greek setting. The Order of the Ancients is the earlier organization featured in Origins and Valhalla, while the Templar Order becomes central in later historical periods. These groups share ideological links in the series but are not interchangeable names.