Iasion was the son of Zeus and the nymph Electra in Greek mythology. Other sources say that his parents were either Zeus and Hemera, or Corythus and Electra. He was the one who started the rituals on the island of Samothrace. He had three sons with the goddess Demeter, named Ploutos, Philomelus and Korybas.
When Iasion attended the marriage of Cadmus and Harmonia, he was seduced by Demeter. Zeus then realised what had happened, and full of jealousy, killed Iasion by hurling a thunderbolt. In some versions of the myth, he was then transformed into the constellation Gemini along with the hero Triptolemus.
Iasion Is also called Iasus, Eetion.