Medusa was a fictional character encountered in the Doctor Who serial, The Mind Robber.
Whilst traversing through the Land of Fiction, the Doctor and Zoe Herriot come across a statue of Medusa. Suddenly, it begins to animate and starts to advance slowly towards them. Knowing what to do, the Doctor and Zoe shifted their gaze away from Medusa's eyes. The Doctor is given the opportunity to strike Medusa down with a sword but realising this would trap him in the world of fiction, he instead produces a small mirror and shows Zoe Medusa's reflection. Defeated, Medusa reverts back to a statue again.