Doctor Who: Classic - The Gunfighters
Doctor Who: Nu-Who - A Town Called Mercy
The Prisoner - Living In Harmony
Star Trek - Spectre of the Gun
Star Trek: The Next Generation - A Fistful Of Datas
Star Trek: Enterprise - North Star
Quantum Leap - The Last Gunfighter
Battlestar Galactica - The Last Warrior
Red Dwarf - Gunmen Of The Apocalypse
Lost In Space - West Of Mars
Any other suggestions? Single episodes and not science fiction shows that are hoss operas in space (i.e Firefly, Westworld)