http://screenrant.com/worst-star-trek-episodes-movies/

Even the best franchises have their rough patches. It can’t be that bad, can it?

For some other awful episodes I'd add:

The Alternative Factor (TOS)
The Way To Eden (TOS)
Conspiracy (TNG)
The Outrageous Okona (TNG)
The Alternate (DS9)
If Wishes Were Horses (DS9) Interesting premise it just wasn't handled well.
And I can't remember the name of the episode but there's a Star Trek: Enterprise episode where crewmember Charles "Trip" Tucker becomes pregnant! Really stupid.

There's probably some more Trek episodes I don't like either but that's what I can come up with for now.

Ed.

For some other awful episodes I'd add:

The Alternative Factor (TOS)
The Way To Eden (TOS)
Conspiracy (TNG)
The Outrageous Okona (TNG)
The Alternate (DS9)
If Wishes Were Horses (DS9) Interesting premise it just wasn't handled well.
And I can't remember the name of the episode but there's a Star Trek: Enterprise episode where crewmember Charles "Trip" Tucker becomes pregnant! Really stupid.

There's probably some more Trek episodes I don't like either but that's what I can come up with for now.

Ed.

The 12 Worst Star Trek Productions–EVER (http://nostalgiarush.blogspot.com/2016/03/the-12-worst-star-trek-productionsever.html)

I agree with most of these but I thought that the last episode of Enterprise wasn't that bad.

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Having already looked at the Top 10 Star Trek episodes (https://www.youtube.com/watch?v=OtexC32m7zQ) of all time, we now do the total opposite: count down the Worst 10 Star Trek episodes of ALL time. Choosing 10 episodes out of 727 episodes of The Original Series (TOS), The Next Generation (TNG), Deep Space Nine (DS9), Voyager (VOY) and Enterprise (ENT) was not easy and no doubt you'll wonder why your favourite turkey isn't here. Let's hope Star Trek: Discovery (DSC) never comes close to having an episode feature in a list like this!

The last episode of the original got trashed by TV Trash. I can see it was that bad.