Poseidon is the god of the sea and protector of all aquatic creatures. Brother of Zeus and Hades, after the overthrow of their father, Cronus, he drew lots with them to share the universe. He ended up becoming lord of the sea. He was widely worshipped by seamen. He married Amphitrite, one of the granddaughters of the Titan Oceanus.
At one point he desired Demeter. To deter him, Demeter asked him to make the most beautiful animal that the world had ever seen. So, in an effort to impress her, Poseidon created the first horse. In some accounts, his first attempts were unsuccessful and created a variety of other animals in his quest; thus, by the time the horse was created, his passion for Demeter had diminished.
His weapon was a trident, with which he could make the earth shake, causing earthquakes, and shatter any object. He was second to Zeus in power amongst the gods. He was considered by Greeks to have a difficult quarrelsome personality. Combined with his greed, he had a series of disputes with other gods during his various attempts to take over the cities they were patrons of.