Pegasus (Greek: Πήγασος, translit. Pḗgasos; Latin: Pegasus, Pegasos) is a winged divine stallion, usually depicted as pure white in color, in Greek mythology. 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.