The brother of Zeus and Hades, Poseidon is ruler of the seas.
Moody and violent when angry, Poseidon would unleash his temper on the seas, turning them wild and dangerous with churning waters and raging winds. When he was really angry— or when his brother, Zeus, asked for back-up, Poseidon would also unleash earthquakes and floods.
Poseidon traveled with an entourage of sea creatures, led by his son and herald, Triton, the bearer of Poseidon’s trident.
Poseidon was a son of Cronus and Rhea, who was swallowed by his father at birth, like all his siblings, except for Zeus. When Zeus freed all his siblings, Poseidon received authority over the seas.
Athena and Poseidon competed over who would be the patron of Ancient Greece’s chief city, Athens. The god who gave the city the best gift would receive the city’s sacrifices. Poseidon gave them horses, but Athena gave them olive trees, which the townsfolk decided was a much better gift, as it provided wood, oil and food.
Despite this perceived snub, Poseidon stayed very active in Athenian affairs. It was because of Poseidon that Odysseus was lost at sea on his way home from the Trojan War.
Poseidon was also responsible for inflicting mortals who displeased him with certain kinds of epilepsy.
Nardo, Don. Greek mythology. Detroit: Gale, Cengage Learning, 2012. Print.
"Poseidon." Wikipedia. Wikimedia Foundation, 6 Nov. 2014. Web. 11 June 2014. http://en.wikipedia.org/wiki/Poseidon