Doctor Arthur Coleman was a former Starfleet chief medical officer, who later served as the expedition surgeon on Dr. Janice Lester's two-year expedition on Camus II.
Coleman was removed from his last starship posting as chief medical officer after Starfleet Command, in cooperation with the Surgeon General's office, cited him for "administrative incompetence" and making "flagrant medical blunders".
In 2267, Coleman joined an expedition headed by Dr. Janice Lester to Camus II as the expedition surgeon. For the next two years, he fell in love with and conspired with Dr. Lester to use a life-entity transfer device to switch her mind into Kirk's body and vice versa. When the plot was foiled and Dr. Lester was deemed insane, he asked to be allowed to care for her. (TOS: "Turnabout Intruder")
Coleman was played by actor Harry Landers.
He was called Howard Coleman in the episode's novelization.