Odds are, if you've been a Star Trek fan for any real amount of time, there are going to be some episodes on this list that you're just waiting to see appear. Star Trek has almost always been about optimism and a bright future, with some exceptions (looking at you, Discovery s1) but that doesn't mean that it hasn't dropped the ball along the way. With issues ranging from writers' strikes to just bad decision making, there are many entries in the canon that should never be shown to aspiring fans. Truly, there are some episodes that only a Mother could love.
This list breaks down the worst of the worst, spread across all of the entries to the franchise. It is very possible that some series will be represented a little more regularly than others but that is not to say that the rest of that series isn't worth the investment. Its just that these episodes are all examples of bad investments.
From supernatural beings to stuck up princesses, stolen brains to plain, old fashioned racism, these episodes are all perfect examples to use if you are looking to turn someone away from Star Trek as whole. Whether we can forgive these entries or not remains to be seen, but here are the 25 WORST episodes of Star Trek ever (so far!)
25. Assignment: Earth - TOS
This is a funny little episode that is on this list for perhaps an unfair reason. It's not a bad hour of television - it's simply a bad episode of Star Trek.
Robert Lansing appears as Colonel Gary Seven, an agent sent from the future. He is a compelling protagonist and his relationship with his assistant Robert Lincoln, played by Terri Garr. Garr famously hated the experience of filming the episode so much she refused to talk about it in later years, citing her fear of being probed by Star Trek questions as the reasons for this.
The episode was written as a backdoor pilot to a potential Gary Seven spin off, with the futuristic agent working in 20th century Earth. Gene Roddenberry was keen on the idea and keen to keep the stars, but as NBC had no involvement in the casting process it seemed a doomed operation from the beginning. Nothing materialised.
Therefore, there is an episode of the Original Series that was openly created to be a different show, separate from the plot of the series. Even the opening scene puts the Enterprise in orbit of 20th century Earth for...reasons to do with research? While the almightly temporal prime directive had not come into effect by that stage, it is a fairly thin plot device to get them there. It's most certainly not the worst episode, but it could be skipped without any loss to the show as a whole.