Star Trek: 10 Times The Ship Was Stolen
9. The Original Kelvan Timeline
By Any Other Name sees the Kelvans take control of the USS Enterprise. In this example, the Starfleet crew are technologically at a loss, while also threatened with reduction to inert solids. Crewman Thompson is the sacrificial lamb that lets the rest of the crew know to stay in their lane.
Though Scotty, Spock, McCoy, and Kirk all play their parts in retaking the ship from the Kelvans, it is truly the aliens' new human forms that is the final decider. Rojan, cajoled by Spock and Kirk, discovers himself to be more Human than Kelvan, thus throwing the entire plan for Kelvan conquest into question.
This could also have been a positive experience (minus what happened to Thompson) for Starfleet, as the Kelvan modifications to the Enterprise's nacelles could have spurred propulsion technology forward by centuries. Alas, that part of the story fell by the wayside, never to be mentioned again,