Drang

 was the leader of the chrononauts of Aoris in Era 24. He thought that the Fourth Doctor was from his planet's past. He then asked the Doctor to deactivate a bomb. (AUDIO: The Paradox Planet)

He recaptured the Doctor and executed Embery. The Doctor told him that he was the cause of all of the problems that Aoris had suffered. He realised that he had to stop the war and he could rewrite history but the Doctor told him how catastrophic this would be. After his efforts failed, he committed suicide. (AUDIO: Legacy of Death)