The Golden Fleece, also known as the Golden Fleecing, is a mythical fleecing made of gold.
The Golden Fleece was originally the fleece of a Golden Ramrod, a creature so rare and magical that rather than making anything from it, its owners decided to hang the Fleece in a temple in Colchis. They also placed two Sleepless Dragons, one walking and one flying, to stand guard, and hired the Harpies, giant hag-faced birds, as additional guardians (and caretakers of the dragons).
In ancient times, Colchis was not yet an abandoned land of myth, and was still inhabited by men, whose princess was the witch-priestess Medea. One day, a hero called Jason came from Greece on a boat called the Argo, seeking the Golden Fleece as a prize to regain his honor. Jason and Medea fell in love and Medea told him how to bypass the dragons and the Harpies. Together, they fled Colchis back to Greece with the Golden Fleece.
However, Medea eventually "got sore" with Jason. She slipped out of their palace with the Fleece in hand and sailed the Argo back to Colchis where she hung the Fleece back in its place in the temple. The Dragon and the Harpies resumed their watch, and did not fail even after the last human inhabitant of Colchis was long dead.
The Harpies entertained themselves through the boredom of these lonely centuries by cooking foul-tasting dishes and having cuisine contests among them. Though this kept them appropriately busy, tensions began to form between them as they quarreled over who was the best cook. After their queen died, they decided to use a final cooking contest to elect their new leader; and, rather than judge between them, they decided to invite a rich (and thus presumably refined) mortal man to taste all the dishes. To tempt the man into following them to Colchis, they promised him access to the Fleece, even though they were just as unable as anybody else to bypass the Sleepless Dragons stationed in the corridor.
The first man to trust them happened to be Scrooge McDuck, who, at that point, wished to obtain a coat made of gold and thought golden wool would be perfect for that end. Unfortunately for the Harpies, one of their ranks decided to cheat by allowing Scrooge to escape with the Fleece if he declared her recipte the winner. This did not entirely go as planned, as Scrooge had to leave part of the Fleece on the eyes of the Sleepless Dragon to force him into sleep.