Pegasus sprang from Medusa’s body after Perseus beheaded her.
According to Greek mythology, Medusa was pregnant by Poseidon when Perseus killed her. When her head was severed, Pegasus, the winged horse, emerged from her neck along with the warrior Chrysaor. This unusual birth explains why Pegasus is connected to Medusa even though he is not a Gorgon.
Pegasus later became associated with the hero Bellerophon, who rode him against the Chimera. The horse was eventually placed among the stars as the constellation Pegasus in later astronomical tradition.
A frequent mistake is to say that Pegasus came from Medusa’s blood alone. The myth more specifically describes the creature emerging from her severed body, while drops of her blood also acquired other legendary effects in different traditions.