King Eurystheus ordered Hercules to complete the Twelve Labors.
Eurystheus was the king of Tiryns and Mycenae in Greek mythology. Because of a complicated dispute involving Zeus, Hera, and the succession to the Argive throne, Eurystheus became king instead of Hercules. Hercules was then required to serve him and perform extraordinary tasks.
The labors were intended as a punishment for Hercules after he killed his wife and children during a divinely caused madness. Eurystheus assigned the tasks and judged whether Hercules had completed them. He rejected two achievements—the killing of the Hydra and the cleaning of the Augean stables—because Hercules had received assistance or payment.
Later storytellers often portray Eurystheus as frightened and jealous of Hercules. In some artistic versions, he hid in a large bronze jar when Hercules returned with Cerberus. Eurystheus is therefore the taskmaster and evaluator of the labors, not the hero who performed them.