Dr. Who (Land of Fiction)
Dr. Who was a version of the Doctor existing in Land of Fiction, inhabiting a more simplistic and less morally ambiguous life than the actual Doctor. Dr. Who has changed as the Doctor himself has regenerated. [Seventh Doctor|The Doctor]] first met him in the Land of Fiction. Dr. Who was created by a teenage human male called Jason who used to be the Master of the Land of Fiction. (NA:Condundrum)
Later, the Doctor would once again meet Jason and come into conflict with Dr. Who in the real universe. (NA: Head Games) Though not actually evil, Dr. Who's simplistic morality tended to lead him into making rash decisions.
Behind the Scenes
The character of Dr. Who first appeared in the New Adventures novel Conundrum as a way to rationalize away the difference between the Doctor as seen in the Doctor Who television series with the version seen early comics and the Doctor Who Annuals who acted, at times, very out of character, and often called himself "Dr. Who". The Eighth Doctor comic The Land of Happy Endings implies that Dr. Who lives in the mind of the Doctor or possibly that the "real" Doctor lives in Dr. Who's.