Harry Sullivan, M.D. -- One of the Doctor's few male companions. Harry was a member of UNIT -- The United Nations Intelligence Taskforce -- and assigned to tend to the Doctor after his third regeneration. During the course of events, Harry wanted to prove, for the patient's own good, that rational, sane people do not travel around time and space in police boxes. He walked into the TARDIS and instead found a very large surprise. Harry stayed aboard until "Terror of the Zygons". Harry's last adventure, albeitly earth-bound, was "Android Invasion". The Doctor's habit of using his old companions' names as aliases began in the Third Series episode "Tooth and Claw". Read Full Review