Greek Mythology: The Birth of Athena

Zeus heard a prophecy that the child of he and Metis (Titan goddess of wise council) would be greater than himself. To prevent this, Zeus swallowed Metis whole. Later Zeus had a splitting headache. Hephaestus then hit Zeus in the head with his hammer (what a loyal son!) which split Zeus's head open. Out of his gaping skull then jumped his fully grown daughter dressed in full battle armor. Probably one of the most bizarre birth stories ever.