Grash

 was a crew member aboard the Vanguard in 2503. He disagreed with Deeva Jansen's captaincy, and created a mutiny as she refused to let him to execute the Eighth Doctor and Charlotte Pollard. His mutiny eventually failed when he fell under the control of the Cybermen, who killed him when he resisted his cyber-conversion and went insane. (AUDIO: Sword of Orion)

Behind the scenes
Grash originally appeared in the Audio Visuals story of the same name, voiced by Nigel Peever.