Medusa

"The medusa was an ugly creature. Let's have a look at how she came into existance, for she wasn't always that ugly... Again, the Gods played their role.
The Medusa was the daughter of Phorkys and Keto, the children of Gaia (Earth) and Okeanos (Ocean). She was one of the three sisters known as the Gorgons. The other two sisters were Sthenno and Euryale. Medusa was the only mortal out of the three. She was once very beautiful and lived far in the north were the sun didn't visit. Being very curious, she wanted to see the sun, and asked the Goddess Athena for permission to visit the south. Athena refused to allow her to visit. The medusa got angry and dared to say that Athena hadn't given her permission because she was jealous of her beauty. that was it! Athena was angered and punished her by turning her hair into snakes and cursing her by making her so ugly that who ever lookes at her eyes would turn into stone." ([link])