The ancient Greek god of the sea, protector of all waters and son of Cronus. After the fall of the Titans Poseidon was allotted the sea. He was worshiped as both a fertility god and the deity in charge of all navigation.
Poseidon was the father of the Pegasus and known in Thessaly as Hippios, god of horses. He was an elder god, a brother to Zeus, and very powerful with a violent and vengeful disposition. He carried a trident that allowed him to cause earthquakes.
His grudge against Odysseus is one of the themes of the Odyssey. Odysseus did not offer reverence to Poseidon after one of his victories, and this went ill with the Sea God. Poseidon was the husband of Amphitrite, who bore him Triton, and by others he fathered many more sons, who usually turned out to be badasses (like Orion) or monsters (Polyphemus).
The Romans identified him with Neptune. See the Poseidon Family for a more detailed lineage.
Greek and Roman Mythology