Medusa was one of three sisters. They were known as The Gorgons. Medusa's sisters were Stheno and Euryale. Medusa was mortal, but her sisters were immortal. They were all children of the sea deities, Phorkys and his sister Keto. Before they were monsters, all three sisters were beautiful young women, particularly Medusa; however, she was a priestess in the temple of Athena and was bound by a vow of celibacy.