Medusa was not the only Gorgon. She had two sisters named Stheno and Euryale. The parents of the Gorgons were Phorcys and Keto. Not much is known about the other two Gorgons other than that they were immortal, whereas Medusa was not. Probably Medusa was mortal to serve the storyline of her beheading by Perseus because no further explanation is provided for this weird fact.
Although the sources do not mention how the other Gorgons looked, we can assume that their appearance was similar to Medusa’s. At least, this is how ancient artists depicted them. Interestingly, in many of these early depictions, the Gorgons appeared with wings. But this apparently did not remain the same throughout the ages.&