Zeus, Poseidon and Hades are the Greek gods of Olympus who ruled over the sky, the sea and the underworld, respectively. Some of the other major Olympian gods are Ares, Athena, Apollo, Artemis and Aphrodite.
Zeus, Poseidon and Hades are brothers, the children of the Titans, Cronus and Rhea. Zeus' symbol and weapon is the thunderbolt, which he throws when he is unhappy. Poseidon's symbol is the trident. When he is unhappy, he causes earthquakes. Hades lives in the underworld and rules over the dead.
Ares, the god of war, is the son of Zeus and his wife and sister, Hera. Athena, who sprang fully grown from Zeus' head, is the goddess of wisdom.
Apollo and Artemis are twins, the children of Zeus and Leto. Apollo is the god of the sun, light, truth and healing. Artemis is the goddess of the hunt and the patroness of hunters and women in childbirth.
Aphrodite is the goddess of love and beauty. She was born from the foam of the water and rose fully grown on a shell, according to some sources, while she was Zeus' daughter by the titan Dione according to others.