LEDA

LEDA: Daughter of King Thestius, she was notorious for swanning around with ZEUS during one of his bird impression phases.

ZEUS had turned her into a swan to avoid detection by the jealous HERA, and in that form she had a lot of fun. Until she discovered she'd conceived and that instead of giving birth, she'd have to lay eggs. Which subsequently hatched into Godlets.

LEDA was married to Tyndareds, a banished heir to the throne of Sparta, and when the eggs arrived two of the yolks were his: CASTOR and Clytemnestra. The other two, POLLUX and HELEN, were ZEUSlings.

There is as usual a subplot to this story for those who like alternative endings:

During his flighty bird behaviour, ZEUS was also chasing after NEMESIS. She misguidedly changed into a goose to try and evade his attentions but got well and truly goosed when ZEUS chose to go as a Gander.

Naturally there was a resultant egg, and as a Goddess of Retribution NEMESIS is said by some to have slipped her egg into LEDA's hatchery — and this is the one that contained POLLUX and HELEN.

Followers of NEMESIS became very confused and some assumed any big white bird with feathers laying eggs must be their beloved Goddess and who the hell was LEDA anyway? But when LEDA died she was deified as NEMESIS just in case she might have been, and ZEUS was left with egg on his face.