In Greek mythology Medea was the daughter of King Aeetes (Georgian Ayeti) of Colchis (Georgian Kolkheti, now a territory of modern Georgia) and niece of Circe, and later wife to Jason. In Greek eyes she was a witch or sorceress; to an archaeologist her powers would be recognized as shamanic.

The myths that involve Medea are part of a class of myths that tell how the Hellenes of the distant heroic age, before the Trojan War, faced the challenges of the pre-Greek "Pelasgian" cultures of mainland Greece, and the Aegean and Anatolia. Jason, Perseus, Theseus, and above all Heracles, are all "liminal" figures, poised on the threshold between the old world of shamans, chthonic earth deities, archaic matriarchies, and the Great Goddess and the new Bronze Age Greek ways.

Medea figures in the myth of Jason and the Argonauts, a myth we know best from a late literary version worked up by Apollonius of Rhodes in the 3rd century BCE and called the Argonautica. But for all its self-consciousness and researched archaic vocabulary, the late epic was based on very old, scattered materials.

Medea's role began after Jason arrived from Iolcus in Colchis to claim the Golden Fleece as his own. In a familiar mythic meme, King Aeetes of Colchis promised to give it to him only if he could perform certain tasks. First, Jason had to plough a field with fire-breathing oxen that he had to yoke himself. Then, Jason had to sow the teeth of a dragon in the ploughed field (compare the myth of Cadmus). The teeth sprouted into an army of warriors. Jason was forewarned by Medea, however, and knew to throw a rock into the crowd. Unable to decipher where the rock had come from, the soldiers attacked each other and defeated each other. Finally, Aeetes made Jason fight and kill the sleepless dragon that guarded the fleece. Medea put the beast to sleep with her narcotic herbs. Jason then took the fleece and sailed away with Medea, who had fallen in love with him. Medea distracted her father as they fled by killing her brother, Apsyrtus. In the flight, Atalanta was seriously wounded but healed by Medea.

On the way back to Thessaly, Medea prophesied that Euphemus, the Argo's helmsman, would one day rule over all Libya. This came true through Battus, a descendant of Euphemus.

The Argo then came to the island of Crete, guarded by the bronze man, Talos. Talos had one vein which went from his neck to his ankle, bound shut by only one bronze nail. Medea cast a spell on Talos to calm him; she removed the bronze nail and Talos bled to death. The Argo landed.

While Jason searched for the Golden Fleece, Hera, who was still angry at Pelias, conspired to make him fall in love with Medea, whom she hoped would kill Pelias. When Jason and Medea returned to Iolcus, Pelias still refused to give up his throne. Medea conspired to have Pelias' own daughters kill him. She told them she could turn an old ram into a young ram by cutting up the old ram and boiling it (alternatively, she did this with Aeson, Jason's father). During the demonstration, a live, young ram jumped out of the pot. Excited, the girls cut their father into pieces and threw them into a pot. Pelias did not survive.

Having killed Pelias, Jason and Medea fled to Corinth.

When Jason deserted Medea for Glauce, daughter of the Corinthian King Creon, she killed Glauce, Creon, and her own two children and fled to Athens. Alternatively, Jason married Creusa, daughter of Creon. Medea got even by giving Creusa a cursed dress that stuck to her body and burned her to death as soon as she put it on, a transformation of the mythic element in the story of Heracles and Nessus.

The tragic situation of Medea, abandoned in Corinth by Jason, was the subject matter transformed by Euripedes in his tragedy Medea, first performed in 431 BCE.

Some said Medea married Achilles.

Fleeing from Jason, Medea made her way to Athens and married Aegeas. They had one son: Medus, father of Theseus, whom he had abandoned as a baby. When Theseus returned to Athens, he did not reveal his true identity. He was welcomed by Aegeas, who was suspicious about the stranger who came to Athens. Aegeas' wife, Medea, tried to have Aegeas kill Theseus by asking him to capture the Marathonian Bull, but Theseus succeeded. She tried to poison him but at the last second, Aegeas recognized Theseus by his sandals, shield and sword and knocked the wine cup out of Theseus' hand. Father and son were reunited.

Medea, with Medas, fled Athens. She founded Media.

Apollonius Rhodius, Argonautica; Apollodorus, Bibliotheke I, 23-28; Ovid, Metamorphoses VII, 1-424; Euripides, Medea.