The Twelve Labors of Heracles

After Hera drove Heracles to a fit of madness in which he killed his wife and children, the Oracle at Delphi commanded him to serve King Eurystheus of Tiryns and perform ten labors (later expanded to twelve when Eurystheus rejected two). The labors began with slaying the Nemean Lion, whose hide was impervious to weapons - Heracles strangled it and wore its skin as armor. He then killed the Lernaean Hydra, a many-headed water serpent that grew two heads for every one severed, with help from his nephew Iolaus who cauterized each stump. He captured the Ceryneian Hind, sacred to Artemis, and the Erymanthian Boar. He cleaned the Augean Stables in a single day by diverting two rivers. He drove away the Stymphalian Birds, captured the Cretan Bull, and tamed the Mares of Diomedes. He obtained the Girdle of Hippolyta, queen of the Amazons, and herded the Cattle of Geryon from the far west. He retrieved the Golden Apples of the Hesperides, guarded by a hundred-headed dragon, by tricking Atlas into fetching them while Heracles temporarily held up the sky. For his final and most daunting labor, he descended into the underworld and captured Cerberus, the three-headed guardian of the dead, with his bare hands - then returned the beast unharmed. Having completed all twelve labors, Heracles was purified of his guilt and set on the path toward eventual immortality.

Apollodorus is the source that ties the twelve into one continuous sequence with a stated cause: Eurystheus set ten labors, then refused to count the Hydra, because Iolaus had helped, and the Augean stables, because Heracles had accepted payment for the work, and set two more to bring the total to twelve. Earlier art and poetry knew many of the same feats as separate, freestanding stories rather than a fixed, numbered list - the canonical count and order that most readers know today is a later systematization rather than the shape the earliest tradition took.

Rome added an Italian sequel to the cattle of Geryon: Livy has Hercules kill the thief Cacus on the site of Rome (Ab Urbe Condita 1.7.3-7). The Greek and Roman tellings are compared in Heracles vs Hercules.