In Ancient Greek religion and mythology, Zeus is the god of thunder and the sky; he is the ultimate ruler of all of the gods and goddesses on Mount Olympus. He is married to Hera, the goddess of femininity, fertility and family, who also happens to be his sister. Zeus and Hera are the leaders of the Twelve Olympians—the most powerful deities in Greek mythology.

The Roman equivalent of Zeus is Jupiter, also called Jove. Just like Zeus, Jupiter is also the god of thunder and the sky and he is the king of all gods and goddesses. In fact, there are no actual meaningful differences among the two deities; Jupiter is simply Zeus's Roman name. Thus, Jupiter also married his sister—Juno, the goddess of childbirth and marriage and the equivalent of Hera in Greek mythology. Both Zeus and and Jupiter have the same symbols—the eagle, the thunderbolt and the oak tree, and occasionally the lion as well.

In ancient times, the majority of the Roman population worshiped Jupiter as the supreme leader of the Roman gods and goddesses. This changed when the Western Roman emperor Constantine made Christianity, as well as the other religions of that time, legal in the Roman Empire and allowed for their spread across Roman territory.