In Greek mythology, the winged horse ridden by Bellerophon was Pegasus.
Pegasus was a divine winged horse associated with springs, poetry, and heroic legend. In the most familiar account, he sprang from the blood of Medusa after the hero Perseus beheaded her. Pegasus later became the mount of Bellerophon, a hero who used him to fight the Chimera, a fire-breathing monster with a lion’s head, a goat’s body, and a serpent’s tail.
Bellerophon captured Pegasus with help from Athena, who gave him a golden bridle, or in some versions received the bridle through a dream involving the goddess. The hero’s success eventually led to overconfidence. He attempted to ride Pegasus to Mount Olympus, but Zeus punished the attempt, and Bellerophon fell.
Pegasus should not be confused with Arion, another extraordinary horse in Greek mythology. Arion was immortal and could speak, while Pegasus is specifically famous for his wings and connection with Bellerophon.