The Gorgons
The Gorgons where 3 ugly sisters. They had a deadly stare that would turn you to stone. Wings and snake for hair with razor sharp husks, and brass claws. The 3 sisters were Stheno, Euryale, and of course Medusa.  Stheno and Euryale were born Gorgons and therefore were immortal. Medusa on the other hand being turned into a Gorgon. Stentho and Euryale were the children daughters of Gaia, who made them to help aide her children the Titans against the olympian gods.
Medusa was born to Phorcys and Ceto. Medusa was beautiful until a bad run in with the Goddess Athena, who turned her into a Gorgon, and hid her away on an island. Stheno and Euryale lived on the outer edge of the underworld, near the enterance. Not everything about the Gorgons are all bad. If blood was taken from the right side of a Gorgon it had the healing powers to bring people back from the dead, but you had to be careful because blood taken from the left side of the gorgon was poison. It was said that a picture of one of the Gorgons would scare of evil, so many people in Greece had a Gorgon door knocker or statue outside of their home, to protect them from evil. Medusa was eventually killed by a young hero by the name Perseus. Stheno and Euryale being immortal lived on for ever.