Q: Context: In Greek mythology, the Golden Fleece (Greek: χρυσόμαλλον δέρας chrysómallon déras) is the fleece of the gold-haired winged ram, which was held in Colchis. The fleece is a symbol of authority and kingship. It figures in the tale of the hero Jason and his crew of Argonauts, who set out on a quest for the fleece by order of King Pelias, in order to place Jason rightfully on the throne of Iolcus in Thessaly. Through the help of Medea, they acquire the Golden Fleece. The story is of great antiquity and was current in the time of Homer (eighth century BC). It survives in various forms, among which the details vary.

Question: who led the argonauts in search of the golden fleece? Let's give stream of consciousness first:
The relevant sentence in the passage is: It figures in the tale of the hero Jason and his crew of Argonauts, who set out on a quest for the fleece by order of King Pelias, in order to place Jason rightfully on the throne of Iolcus in Thessaly. Therefore, the final answer is the hero Jason.