in Greek mythology, an enchantress who helped Jason, leader of the Argonauts, to obtain the Golden Fleece from her father, King Aeëtes of Colchis. She was of divine descent and had the gift of prophecy. She married Jason and used her magic powers and advice to help him. In one version, when they fled and were pursued by Aeëtes, Jason, in conspiracy with Medea, cut her brother Apsyrtus to pieces and threw him into the sea to delay the pursuit.

The Medea of Euripides takes up the story at a later stage, after Jason and Medea had fled Colchis with the fleece and had been driven out of Iolcos because of the vengeance taken by Medea on King Pelias of Iolcos (who had sent Jason to fetch the fleece). The play is set during the time that the pair lived in Corinth, when Jason deserted Medea for the daughter of King Creon of Corinth; in revenge, Medea murdered Creon, his daughter, and her own two sons by Jason and took refuge with King Aegeus of Athens, having escaped from Corinth in a cart drawn by dragons sent by her grandfather Helios. After fleeing Corinth, Medea became the wife of Aegeus, who later drove her away after her unsuccessful attempt to poison his son Theseus. The Greek historian Herodotus related that from Athens Medea went to the region of Asia subsequently called Media, whose inhabitants thereupon changed their name to Medes.

Medea also is the heroine of Seneca's Medea, a tragedy based on Euripides' drama, and a number of modern settings, including plays by the 19th-century Austrian dramatist Franz Grillparzer and the 20th-century French playwright Jean Anouilh and operas by the Italian-French composer Luigi Cherubini (1797) and the French composer Darius Milhaud (1939).