Jason was an ancient Greek mythological hero who was famous for his role as the leader of the Argonauts and their quest for the Golden Fleece. He was the son of Aeson, the rightful king of Iolcos. He was married to the sorceress Medea. Because he belongs to mythology, he may have existed before the Greek Dark Ages (1100-800 BC.) The people who wrote about Jason lived around 300 BC, during Antiquity. They wrote about him with the intent that he existed 2,000 years before the start of the development of the Western World.

Jason appeared in various literature 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 of the classical world, as he is seen as being the mythical founder of the city of Ljubljana, the capital of Slovenia.