Zeus is the supreme god of the Greek pantheon, the youngest of his siblings. He became the ruler of the gods through patricide. Zeus is the son of Cronus and Rhea, the two rulers of the previous generation of gods (the Titans). After
growing up in secret exile, he returned to Mount Olympus to slay his father and liberate his siblings. When he and his brothers and sisters were victorious, Zeus claimed the skies as his domain.
Each type of mythology (be it Norse, Mesopotamian, or Greek) has a powerful adulterer god in it. For Greek mythology, this is Zeus, who has slept with many women that are not his wife. Zeus is the father of several gods, such as Ares, Athena, and Aphrodite. Because of his romantic escapades, he has also fathered many bastard children on some of his mortal lovers. The most famous examples of such outcomes are Herakles, Perseus, and Helen of Troy.
The King of mount Olympus is also known as the god of harmony, order, thunder, and the family (or should we say families, given his tendency for adultery). He is married to Hera, who is also his sister. Not surprisingly, their marriage is a difficult one.