Star Trek: 11 Greatest Unfinished Story Ideas

4. The Planet Killer (TOS: The Doomsday Machine) The Doomsday Machine is one of the most tense, action-filled episodes of the franchise, featuring a great premise coupled with award-winning writing and brilliant pacing. The Enterprise discovers the Constellation adrift and nearly destroyed by the planet killer. Its sole survivor, Commodore Matt Decker, is barely clinging to the last shreds of his sanity. With Kirk stranded on the derelict Constellation and the planet killer rapidly approaching the most densely populated parts of the galaxy, it is only by detonating the Constellation inside the planet killer that disaster is averted, and the weapon destroyed. Interestingly, a number of the questions that would naturally have arisen in the wake of The Doomsday Machine are addressed in the episode itself: it is determined that the planet killer originated from somewhere outside of the Milky Way. Its superior construction and advanced weaponry makes it a safe bet that it was built by a civilization more advanced than the Federation. It is theorized that it was intended as a deterrent in an ancient war, but at some point was set loose, possibly destroying both sides in said conflict. The possibilities for future storylines involving the origin and purpose of the planet killer could have been nearly limitless. What two ancient powers were at war with each other when it was built? Was the planet killer actually intended to travel indefinitely across the cosmos? Did it have an overriding mission that it failed to complete? Was it more than a machine and in fact a life-form of some kind, possessing consciousness and an awareness of what it was doing? Regrettably, we are left to wonder. (One quick note: though never revealed in Star Trek: The Motion Picture, it was suggested by the studio, and generally believed by fans, that Commodore Decker was in fact the father of Will Decker .)