Though Jason and the Argonauts have to face a ton of enemies in order to get the Golden Fleece, their biggest obstacle is King Aeëtes, the ruler of Colchis. This son of Helios, the god of the sun, is super suspicious of Jason from the moment he sets eyes on the hero. He tells Jason that he can have the Fleece as long as he can complete three pretty impossible tasks. Unfortunately for the King, his daughter Medea betrays him and shows Jason how to complete the tasks.
Aeëtes mirrors several other mythological kings. For one, there's King Minos of Crete, also a son of Helios, who is betrayed by his daughter, Ariadne, when the Greek hero Theseus comes to town. There's also King Eurystheus who sends Heracles off on 12 seemingly impossible Labors, hoping he will die. And, of course, there's King Pelias, Jason's wicked uncle, who sent the young hero off to fetch the Golden Fleece in the first place.