Who was poseidon?

Poseidon is the Greek god of the sea, brother of Zeus, Hades, Hera, Demeter, and Hestia. He is the second youngest god from the original six (Kronos' children). He is really powerful and has a Trident that, when struck on the ground, creates an earthquake. This earned him the nickname Earth Shaker. He and Zeus often have disputes which may get violent. His domain is the ocean (obviously) and his Trident can do many things, including: control sea currents, cause earthquakes, and turn a person into seawater.