Medusa

Medusa”
Anthony Frederick Sandys (1829-1904)

In Greek
Mythology Medusa (Greek: Μέδουσα (Médousa), “guardian, protectress”)
was a Gorgon, a cothonic female monster, and a daughter of Phorcys and
Ceto;
Only Hyginus, (Fabulae, 151) interposes a generation and
gives another cohthonic pair as parents of Medusa; gazing directly upon
her eyes would turn onlookers to stone. She was beheaded by the hero
Perseus, who thereafter used her head as a weapon until he gave it to
the goddess Athena to place on her shield.
In classical antiquity the image of the head of Medusa appeared in the evil-averting device known as the Gorgoneion.
Source Wikipedia