In Greek mythology who is punished by the poseidon for boasting about her beauty?

In Greek mythology, the mortal woman punished by Poseidon for boasting about her beauty is Medusa. Originally a beautiful maiden, she was transformed into a Gorgon by Athena after Poseidon violated her in Athena's temple. As a result of her transformation, Medusa became terrifying, with snakes for hair and the ability to turn anyone who looked at her into stone.