The Medusa was an ugly creature. Let's have a look at how she came into existence, 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 Gaea (Earth) and Oceanus (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 originally a golden-haired and very beautiful maiden, who, as a priestess of Athena, was devoted to a life of celibacy; but, being wooed by Poseidon, whom she loved in return, she forgot her vows, and became united to him in marriage. For this offence she was punished by the goddess in a most terrible manner. Each wavy lock of the beautiful hair which had so charmed her husband, was changed into a venomous snake; her once gentle, love-inspiring eyes now became blood-shot, furious orbs, which excited fear and disgust in the mind of the beholder; whilst her former roseate hue and milk-white skin assumed a loathsome greenish tinge.
Seeing herself thus transformed into so repulsive an object, Medusa fled from her home, never to return. Wandering about, abhorred, dreaded, and shunned by all the world, she now developed into a character, worthy of her outward appearance. In her despair she fled to Africa, where, as she passed restlessly from place to place, infant snakes dropped from her hair, and thus, according to the belief of the ancients, that country became the hotbed of these venomous reptiles. With the curse of Athene upon her, she turned into stone whomsoever she gazed upon, till at last, after a life of nameless misery, deliverance came to her in the shape of death, at the hands of Perseus.
Adventures of Perseus,