Poseidon was the god of oceans, rivers, flowing water and earthquakes. Brother of Zeus and Hades, he was married to the sea-nymph Amphitrite, but had no children with her. He had a reputation for being rather violent and bad-tempered. He had numerous affairs, all fruitful, but the offspring were rather unusual, such as Polyphemos the one-eyed Cyclops and Pegasus the winged horse.

With his trident he would strike the ocean floor to summon violent tempests and earthquakes. He could also bring an end to a storm or an earthquake with one strike of his trident. He is also thought to have struck a rock with his trident, to create the very first horse, Skyphios. His subsequent association with horses is reflected in his epithet 'tamer of horses'.