Encyclopedia Britannica"Pegasus, in Greek mythology, a winged horse that sprang from the blood of the Gorgon Medusa as she was beheaded by the hero Perseus. With Athena’s (or Poseidon’s) help, another Greek hero, Bellerophon, captured Pegasus and rode him first in his fight with the Chimera and later while he was taking vengeance on Stheneboea (Anteia), who had falsely accused Bellerophon. Subsequently Bellerophon attempted to fly with Pegasus to heaven but was unseated and killed or, by some accounts, lamed. The winged horse became a constellation and the servant of Zeus. The spring Hippocrene on Mount Helicon was believed to have been created when the hoof of Pegasus struck a rock."