Medusa

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Medusa is the monstrous lady whose head Perseus chops off. She is a Gorgon and, like her sisters, Stheno and Euryale, she has snakes for hair, bronze hands, wings, and tusks. Medusa and her fellow Gorgons are so hideous that they turn anyone they look at into stone. Though she is known to be this scary monstrous lady, she was not awake when Perseus came to kill her.

However, in a different depiction of the story, she used to be a very pretty girl who was unfortunate enough to chatch the eye of god Poseidon. He forced her to sleep with him in the sacred temple of Athena, which made Athena mad. However, she did not punish her uncle, Poseidon, instead she went after Medusa and turned her into a hideous Gorgon. Medusa was so ugly that her mere glance would turn a man to stone.