Definition: Eurystheus was a grandson of Perseus and Andromeda. Eurystheus' father was Sthenelos. This makes Hercules a cousin of Eurystheus. Since Eurystheus was born before Hercules, he became king of Mycenae and Tiryns. In the story of Hercules told by Apollodorus, Hercules serves Eurystheus for 12 years as penance for killing his own children. Eurystheus set before Hercules seemingly impossible tasks (or else the Pythian dictated them) that the king did not profit from. Eurystheus seemed to be afraid of Hercules, but survived the hero and after his death feared the retribution of the children of Hercules. Iolaus or Hyllus may have killed Eurystheus.