Jason (; Greek: Ἰάσων Iásōn [i.ǎː.sɔːn]) was an ancient Greek mythological hero who was the leader of the Argonauts whose quest for the Golden Fleece featured in Greek literature. He was the son of Aeson, the rightful king of Iolcos. He was married to the sorceress Medea. He was also the great-grandson of the messenger god Hermes, through his mother's side.
Jason appeared in various literary works in the classical world of Greece and Rome, including the epic poem Argonautica and the tragedy Medea. In the modern world, Jason has emerged as a character in various adaptations of his myths, such as the 1963 film Jason and the Argonauts and the 2000 TV miniseries of the same name.
Jason has connections outside the classical world, being the mythical founder of the city of Ljubljana, the capital of Slovenia.