Poseidon (Roman name: Neptune)
Poseidon was god of the sea. He was the most powerful god except for his brother, Zeus. He lived in a beautiful palace under the sea and caused earthquakes when he was in a temper. His symbols include the horse and the trident (a three-pronged pitchfork).
After the fall of the Titans, Poseidon was allotted the sea. He was worshiped especially in connection with navigation; but as the god of fresh waters he also was worshiped as a fertility god. In Thessaly and other areas he was important as Hippios, god of horses, and was the father of Pegasus.
Poseidon was represented as extremely powerful, with a violent and vengeful disposition. He carried the trident, with which he could split boulders and cause earthquakes. When Laomedon failed to pay him for building the walls of Troy, Poseidon sent a sea monster to ravage the Troad and years later vengefully assisted the Greeks in the Trojan War. His grudge against Odysseus is one of the themes of the Odyssey.
He was the husband of Amphitrite, who bore him Triton, and by others he fathered many more sons, who usually turned out to be strong, brutal men (like Orion) or monsters (like Polyphemus). The Romans identified him with Neptune.