The Gorgon Medusa was a monstrous, yet mortal creature that had the power to turn anyone who looked at her into stone.
Medusa and two sisters of hers, Stheno and Evryale, were Gorgons, with frightful eyes, brass hands and living snakes on their head instead of hair. Medusa was the only Gorgon who was mortal, however she was more powerful than her sisters.
Medusa got finally killed by Perseus, the founder of Mycenae. Her head was given to Athena, the goddess of wisdom and the goddess took the head and placed it on her aegis.