In Greek mythology, Geryon, son of Chrysaor, was a winged giant with three heads, six arms and six legs who lived on the island of Erytheia, said only to be in the far west of the Mediterranean. A two-headed dog named Orthrus and a man named Eurythion guarded the cattle. Heracles killed Geryon and stole the cattle as one of his Twelve Labors. Alternatively, Menoetius, Hades' shepherd, warned Geryon of Heracles' thievery.
While Heracles traveled to Erytheia, he crossed the Libyan desert and was so frustrated at the heat that he shot an arrow at Helios, the sun. Helios begged him to stop and Heracles demanded the golden cup which Helios used to sail across the sea every night, from the west to the east. Heracles used this golden cup to reach Erytheia.
Heracles killed Orthrus and then Eurythion. Heracles killed Geryon and tore his body into three pieces. Heracles then had to herd the cattle back to Eurystheus. In Italy, Cacus, a giant, stole some of the cattle as Heracles slept. He made the cattle walk backwards so they left no trail. Heracles drove his remaining cattle past a cave, where Cacus was hiding the stolen ones, and they began calling out to each other. Heracles killed Cacus. To annoy Heracles, Hera sent a gadfly to bite the cattle, irritate them and scatter them. Hera then sent a flood which rose the water level of a river so much Heracles could not ford the cattle. He piled stones into the river to make the water shallower. Heracles then had to killed a monster that was half-woman and half-serpent. When he finally reached the court of Eurystheus, the cattle were sacrificed to Hera.