He was the god of the sky and the ruler of the Olympian gods. Zeus overthrew his Father Cronus. He then drew lots with his brothers Poseidon and Hades. Zeus won that draw so he became the supreme ruler of the gods. He is the lord of the sky, and the God of rain. His weapon is a thunderbolt which he hurls at those who displease him. He was married to Goddess Hera but, was famous for his many affairs. He is also known to punish those that lie or break oaths. His breastplate was the aegis, the bird that symbolizes him the eagle, his tree the oak. He is presented as the god of justice and mercy, the protector of the weak, and the punisher of the wicked.
Source: http://www.greekmythology.com/Olympians/Zeus/zeus.html
