The Ancient Greeks believed in many gods and goddesses, known as the Greek pantheon, who had human emotions and interacted with humans. The early pantheon included the Titans, who were overthrown by the Olympians led by Zeus in the legendary War of the Titans. Hesiod's 8th century BC work Theogony details the origins of the universe and genealogy of the gods, including Zeus' birth and rise to power over the Titans.