Medusa
Μέδουσα
Youngest of the three Gorgon sisters, with snakes for hair.
Of the three sisters, she alone was mortal.
Ovid tells that she was once a beautiful woman, violated by Poseidon in Athena's temple and then turned into a monster by Athena.
The head Perseus cut off was set into Athena's shield, the aegis. Even in death, it turned onlookers to stone.
SourcesHesiod, Theogony · Ovid, Metamorphoses
Commonly confused
The version where she is cursed after the assault comes from the Roman poet Ovid. In the older Greek tradition, the Gorgons were born monsters from the start.