A search revealed this discussion was had 10 years ago but there have been so many shows gone, and come and gone, since then I think it’s been long enough the question could be asked again.
So… in your opinion, what TV series had the worst ending?
While I disagree with the level of frothing screaming involved, I think my own personal worst one has to be “Lost” for the same reasons that have been stated and restated many times on this board. Mainly, I’ll just blame wasted potential.
-Joe
I’d have to agree with LOST.
I very much disliked the X-Files ending for much the same reasons as LOST, only the level of disappointment in LOST was exponentially higher, probably due to the fact that I had stopped watching X-Files regularly long before it ended, and we were all led to believe that there would be a satisfying resolution to LOST whereas it had become a foregone conclusion that X-Files was never going to solve anything.
I haven’t seen many TV series endings because I don’t watch TV very often, but I agree with Merijeek that the finale of Lost was just a shitwreck. They should have ended it with Sayid kicking a dragon’s dick off while Sawyer, Jack, and Kate had a foxy threeway.
As soon as I saw the title I thought of Lost. Really sad.
Star Trek: Voyager
[SPOILER]
The whole point of the series was them getting back. That was what it all built up to. And (IIRC) it ends with the ship flying towards earth. No payoff whatsoever.
Shit, like pretty much the rest of Voyager.[/SPOILER]
In addition to agreeing with the above opinions about the Lost ending, I’d have to go with the ending to HBO’s Oz, although it did gradually decline in quality over the last three seasons, to the point of the ridiculous “fuck you, loyal viewers” of an ending.
Thing was, though, there were so few parts to Voyager that really made me care. Remember the episode where they killed Garrett Wang (funny, I can remember the actor’s name but not the character’s)…and then replaced him with a clone from a parallel universe? Ugh. Once they’ve done something like that who cares anymore?
-Joe
Kind of cool how the first and last episodes ended with Janeway giving the same command, though. 
Lost, duh.
Battlestar Galactica.
God did it.
I suspect that the only way this thread will be interesting is if you modify your question to say “Aside from Lost, which TV series had the worst ending?”
Probably. These are pretty much the responses I was expecting, considering the LOST finale was relatively recent and so bad.
St. Elsewhere. That is all.
Lost and Battlestar Galactica certainly vie for the top spots. My problem with both those choices is that each show’s quality had fallen and I cared less about them as the end approached.
Not including the TV movie, which had not been green-lit when the finale aired, the worst series ending was Farscape. The worst part was that had credits rolled 15 seconds earlier, the series would have ended on an incredibly high and happy note (and also ended before quality started declining precipitously). But (I think) the producers were upset that the show was canceled and sets struck during post production that he refused to cut the last 15 seconds and even worse, Bonnie Hammer and the SciFi brass didn’t override him.
Abso-frakking-lutely.
(note–I removed some of the white space in the quote. I think that is allowable.)
Lost and BSG. No question.
St. Elsewhere.
Tommy did it.
So what? Couples break up all the time. 
Lost, definitely.
Voyager was probably objectively worse, but I was much less invested in that show. I didn’t even see the final episode until years after it had aired, and then was like, “Seriously?” But even though it was an awful ending, I didn’t have the same “throw my shoe at the TV” feeling that I did after Lost.