Duncan (The Fallen)

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

Biography
Duncan assisted Grace in her experiments on humans and Time Lords. Duncan 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 whilst trying to stop the Master and Donald Stark. (DWM: The Fallen)