Duncan (The Fallen)

From Tardis Wiki, the free Doctor Who reference

Duncan was an MI6 agent in the 21st century. He was a close ally of Grace Holloway and later, the Eighth Doctor.

Duncan assisted Grace in her experiments on humans and Time Lords. He arrested the Doctor and Izzy Sinclair until he realised the Doctor was a Time Lord and a close friend of Grace's. He was killed by the Master whilst trying to stop Donald Stark. (COMIC: The Fallen)