Medusa, meaning “guardian, protectress” was a Gorgon, a chthonic female monster, and a daughter of Phorcys and Ceto. Of the three mythological Gorgon sisters (Euryale, Medusa and Stheno), Medusa was the only mortal one.
Originally Medusa was a very beautiful maiden with luscious and soft hair. She grew up and became a priestess in one of goddess Athena’s temples. Like all priestesses she was bound by an eternal oath of chastity. Poseidon (“God of the Sea”) saw the beautiful Medusa one day and raped her in Athena’s temple. The goddess, enraged by the fact, could not harm Poseidon and so she unleashed her rage on Medusa. She punished Medusa by turning her into a horrifying monster, with hair made from snakes and the ability to turn onlookers into stone. As further punishment Athena exiled Medusa to an island on the western edge of the world, were she awaited her fate. Years passed and eventually Perseus showed up with a magic shield that was given to him by Athena to slay the poor girl- chopping off her head. From her headless neck sprung out Pegasus, a winged horse and a giant with a gold sword named Chrysaor. It is said that these were the children of Poseidon trapped inside the beast due to her punishment.
Perseus used Medusa’s head as a weapon during subsequent battles prior to returning to Athena. Athena then took the head from Perseus and threw it into her shield where it remained.