Thésée (Theseus) is an opera by the composer François-Joseph Gossec, first performed at the Académie Royale de Musique on 1 March 1782.
Princess Églé is in love with Thésée and prays for his safe return from battle against rebels who are threatening King Égée of Athens.
Égée is jealous of Thésée's popularity with the people of Athens, who want to make him the king's heir because of his bravery in battle.
Médée threatens Églé that she will use her magic against her if the princess does not renounce her love for Thésée and marry the king instead.
She conjures up a vision of a terrifying desert full of monsters and also menaces Églé with demons from hell.