Poseidon was one of the twelve Olympian gods that made up the main gods (the pantheon) in Greek religion. He was the controller of the ocean, the "God of the Sea". He was also called "Earth-Shaker" because he caused earthquakes, and the "tamer of horses".

Poseidon was also the protector of many Ancient Greek cities, but not as powerful as Athena, who controlled Athens. The island of Atlantis was the chosen home of Poseidon. It later disappeared under the waves.