In Greek legend, the leader of the Argonauts .
He was the son of Aeson, king of Iolcos in Thessaly. Raised by Chiron after his father's half-brother Pelias seized Iolcos, he returned as a young man and was promised his inheritance if he could bring back the Golden Fleece. After an adventurous voyage, he won the fleece with the help of Medea . He married her, and the two returned to Iolcos, where Medea murdered Pelias. Driven out by Pelias's son, they sought refuge with King Creon of Corinth. When Jason deserted Medea for Creon's daughter, Medea killed her own children by Jason.