Cato Kelgoth

 was a survivor of a Dalek attack. The ship he was on drifted into Gallifrey's orbit and Leela took him home. He wore the uniform of the tech and ordinance corps. The Eleventh General asked him about which ship he came from. He had stolen the Dalek ship as he knew it would be useful for the war effort. He warned about a Dalek weapon and told Vibax how to arm it, killing 1000 Time Lords in retaliation.

Ollistra wanted to place him on Shada for this. Leela was sent to interrogate him for why he had the bomb detonated. He did it as retaliation for the General and Ollistra ordering the destruction of the ship. He thought the Time Lords were just as bad as the Daleks and tried to convince the General of this. He was exiled had his biology rewritten to be human placing to at a random place in time at the TARDIS's whim. He was erased from the matrix as well. However Ollistra had Veklin him assassinated instead. (AUDIO: The Passenger)