Bryan Stoker

Mr B. Stoker was the head of the Royal Hope Hospital in London and supervisor to Martha Jones. When Royal Hope was transported to the Moon, he was killed by the Plasmavore "Florence Finnegan" by having his blood sucked out.

Behind the Scenes
It is unknown what, Stoker's first name was but B. Stoker is an obvious reference to Bram Stoker, the author of Dracula since the alien that killed him was a vampire.