Wasn't Medusa from the Greek Mythos once beautiful?

Depends on what version. The version you're referring to has Medusa the Gorgon being the lover of Poseidon. read more

Medusa was a priestess of Athena, beautiful enough to attract the eye of Poseidon himself. She and Poseidon had an affair and one night, Athena caught them desecrating (read as: screwing each other in) her temple. read more

Until one day Medusa and her friends went to the Parthenon. It was Medusa's first time going to the Parthenon. The Parthenon was the biggest temple in Greece. In the Parthenon was the goddess of wisdom and that was Athena. There was statues of most of the gods and goddesses in the Greek culture. read more

Medusa – whose name probably comes from the Ancient Greek word for “guardian” – was one of the three Gorgons, daughters of the sea gods Phorcys and Ceto, and sisters of the Graeae, Echidna, and Ladon. read more