METIS

METIS: The first Mrs ZEUS. She was the Goddess of Wisdom and ZEUS was warned that any resulting children would be much smarter than him.

Now any sensible God would have abstained from sex, but randy ZEUS was so turned on by her shape-shifting abilities that he couldn't resist. So when she became pregnant he remembered the prophecy and decided to take precautions. (Better late than never.) So he swallowed METIS whole — but himself gave birth to ATHENA, Goddess of Wisdom, making him sadder but wiser.

One or two sources claim that METIS is also the mother of PORUS.