Pegasus is a winged horse in Greek mythology, usually depicted as a white stallion. He was sired by Poseidon, in his role as horse-god, and foaled by the Gorgon Medusa. Pegasus was the brother of Chrysaor, both born from Medusa's blood when their mother was decapitated by Perseus. Greco-Roman poets wrote about his ascent to heaven after his birth and his obeisance to Zeus, who instructed him to bring lightning and thunder from Olympus.