In Greek mythology, the Golden Fleece (Greek: Χρυσόμαλλον Δέρας) is that of the winged ram Chrysomallos (Χρυσόμαλλος). It figures in the tale of Jason and his band of Argonauts, who set out on a quest for the Fleece in order to place Jason rightfully on the throne of Iolcus in Thessaly. The story is of great antiquity – it was current in the time of Homer (eighth century BC) – and consequently it survives in various forms, among which details vary. Thus, in later versions of the story the ram is said to have been the offspring of the sea god Poseidon and Themisto (less often, Nephele). The classic telling is the Argonautica of Apollonius of Rhodes.
Athamas, king of the city of Orchomenus in Boeotia (a region of southeastern Greece), took as his first wife the cloud goddess Nephele, by whom he had two children, the boy Phrixus and the girl Helle. Later he became enamored of and married Ino, the daughter of Cadmus. Ino was jealous of her stepchildren and plotted their deaths. Nephele, or her spirit, appeared to the children with a winged ram whose fleece was of gold. On the ram the children escaped over the sea, but Helle fell off and drowned in the strait now called after her the Hellespont. The ram took Phrixus safely on to Colchis, on the far (eastern) shore of the Euxine (Black) Sea. Phrixus then sacrificed the ram and hung its fleece on a tree (sometimes an oak tree) in a grove sacred to Ares, where it was guarded by a dragon. There it remained until taken by Jason. The ram became the constellation Aries.