- You may be looking for The Abbess (Out of Time).
The Abbess was originally a human. Possessed by Gorgons, she served as their host on Earth for two hundred years.
She wanted to bring the rest of the Gorgons to Earth using a portal which resembled a well. She was turned to stone when Maria Jackson used a mirror to reflect the Gorgon's power back on itself. (TV: Eye of the Gorgon [+]Phil Ford, The Sarah Jane Adventures series 1 (CBBC, 2007).)
