Medusa
 

The sole mortal of the monstrous Gorgons, slain by Perseus. The fact that the hero used a reflective shield given him by Athena to avoid looking directly at Medusa suggests that the Gorgon had the power of turning to stone whoever looked upon her. But most versions of the myth put it that she turned to stone whoever she looked upon. This was not an issue for Perseus, since Medusa was asleep when he chopped off her head.