Keith Bishop
Keith has an extremely low intelligence level, and during one memorable scene, can't answer a questionnaire read out to him by David Brent, he resorts to the 'don't know' option on each question until prompted for another answer from Brent on a later one, at which point he acknowleges that he's forgotten what the question itself was.
Keith doesn't like his job, describing it as 'filler', but doesn't seem to be able to find a new one. He has a knack of phrasing things to the point, even if they're very crude.