Rascla

Rascla was the leader of the Tormian Toad men and self proclaimed heir to the universe.

Biography
Rascla wanted to conquer the universe and chose the Mitrans as his first target. He experimented with acidic warfare but found no way to pass the Mitran defences.

Rascla caused a malfunction on board the Doctor's TARDIS, forcing it to land on Axa, moon of Rascla's native Torm. From there brought the Fourth Doctor, Sarah Jane Smith and Harry Sullivan to Torm and used a Nucleonic Body Separator to possess the Doctor's body. He planned to use the disguise to infiltrate a peace conference on Mitra B and release deadly germs into the area, killing the Mitrans.

Rascla left in the TARDIS and entered the conference. However, at that point, the Doctor re-entered his body and engaged Rascla in a mental battle for control. The Doctor defeated his opponent and Rascla was killed. (DWA: The Body Snatcher)