Eurystheus (yoo-RISS-thyoos). Cousin of Heracles who assigned him his Labors. King of Mycenae and Tiryns only because of Hera's hatred of Heracles, who was the son of her husband Zeus and the mortal Alcmene. Knowing that Alcmene was about to give birth, Zeus had bragged that one of his descendants was about to be born who would rule over two great kingdoms. Hera tricked him into swearing to this, then retarded Alcmene's delivery. Eurystheus, Zeus's great-grandson, was born first.