Pegasus (Greek: Πήγασος, translit. Pḗgasos; Latin: Pegasus, Pegasos) is one of the best known creatures in Greek mythology. He is a winged divine stallion usually depicted as pure white in color. He was sired by Poseidon, in his role as horse-god, and foaled by the Gorgon Medusa. He was the brother of Chrysaor, born at a single birthing when his mother was decapitated by Perseus. Greco-Roman poets wrote about his ascent to heaven after his birth and his obeisance to Zeus, king of the gods, who instructed him to bring lightning and thunder from Olympus. Pegasus is the creator of Hippocrene, the fountain on Mount Helicon. He was captured by the Greek hero Bellerophon, near the fountain Peirene, with the help of Athena and Poseidon. Pegasus allowed Bellerophon to ride him in order to defeat the monster Chimera, which led to many more exploits. Bellerophon later fell from Pegasus's back while trying to reach Mount Olympus. Both Pegasus and Bellerophon were said to have died at the hands of Zeus for trying to reach Olympus. Pegasus was eventually brought to Olympus by Zeus. There, he was stabled next to Zeus' thunderbolts. One of his duties included carrying Zeus' thunderbolts. He was eventually turned into a constellation. Pegasus is the subject of a very rich iconography, especially through the ancient Greek pottery and paintings and sculptures of the Renaissance.

Etymology Pegasus, as the horse of Muses, on the roof of Poznań Opera House (Max Littmann, 1910) Pegasus on ancient cup of Marlik The poet Hesiod presents a folk etymology of the name Pegasus as derived from πηγή pēgē 'spring, well', referring to "the pegai of Okeanos, where he was born". A proposed etymology of the name is Luwian pihassas 'lightning', and Pihassassi, a local Luwian-Hittite name in southern Cilicia of a weather deity associated with thunder and lightning. The proponents of this etymology adduce the role of Pegasus, reported as early as Hesiod, as the bringer of thunderbolts to Zeus. That interpretation was first suggested in 1952 and remains widely accepted, but Robin Lane Fox (2009) has criticized it as implausible. Michael Brown, who has been studying ancient and medieval Greek poetry in the context of the Greek-North European dialogue, has concluded from his studies that the word Pegasus is a pre-Celtic-PIE word, one that did not evolve into one of the numerous common names listed in both Greek and Western languages. This concept is discussed further in "Linguistics and Classical Theology", by William S. R. Miller, which is based on his work with Charles F. G. Osterhaus's analysis of the word and its relationships to Greek and Italian. The relationship of "Pegasus" to "Cyrillic" is discussed further in his Phrygian Monikers and the Naming of Greek Pronunciation "Cyrillic or Pene-Orthogyrin" and "Pegasus" as an Early Semitic construct. Springs According to early myths, everywhere the winged horse struck his hoof to the earth, an inspiring water spring burst forth. One of these springs was upon the Muses' Mount Helicon, the Hippocrene ("horse spring"). Antoninus Liberalis has suggested, that it was opened at the behest of Poseidon to prevent the mountain swelling with rapture at the song of the Muses. Another spring associated with Pegasus was at Troezen. Hesiod relates how Pegasus was peacefully drinking from a spring when the hero Bellerophon captured him.