Zeus was the son of the Titans, Cronus and Rhea. Cronus had been eating his children but was tricked into eating a rock instead of Zeus. When Zeus matured, he defeated Cronus and freed his siblings among others.
Zeus is the brother of Poseidon and Hades. They drew lots for dominions and Zeus received the sky, while Poseidon received the sea and Hades the underworld. Zeus was the god of thunder and sky and he was the ruler of the Olympian gods.
Zeus was married to Hera but he had many lovers both divine and human (often not consensual). He had many offspring, including gods, heroes and monsters.
The Romans worshiped Zeus under the name Jupiter.