Medusa was one of
the three Gorgons. She had snakes for hair, fangs, and was so
ugly that if anyone looked at her they would be turned to stone.
She was the only mortal Gorgon.
Perseus set out
to kill Medusa. He had heard that if you looked her in the eye,
you would be turned to stone. So when Perseus found her, he looked
at her reflection in his shield and cut off her head.