Marshchild
From Tardis Wiki, the free Doctor Who reference
The Marshchild was a young Marshman who followed the Fourth Doctor into the Alzarian starliner. It was soon captured and taken for experimentation by Dexeter. Just as it was about to be operated on, a psychic link with Romana II made it go berserk. It killed Dexeter and eventually itself when it broke a panel and was electrocuted. (TV: Full Circle)
