Ultimately, all gods evolve from the spirits worshipped in animism. In many cases, the gods and goddesses were absorbed from other cultures, mostly in the Archaic period.
The storm god, Zeus is believed to have come from the ancient Indo-European culture of eastern Europe. Athena, known in the Archaic Greek period as Athene, came from Phoenicia via the Aegean islands. During Roman times, the Greeks syncretised some of the Egyptian gods into their own.