He was also William Shatner's body double as "Evil Kirk" or "Good Kirk" in "The Enemy Within" . Besides his two Star Trek appearances, Eitner played larger roles in many television series and TV movies, including 12 O'Clock High, The Fugitive, Lost in Space, Desilu's Mission: Impossible and Mannix, Columbo, The Rockford Files, M*A*S*H, Cannon and Dynasty, spanning four decades.