I disagree on Twin Peaks.
Twin Peaks was good until they revealed who killed Laura Palmer, and then it lost a lot of steam, particulary when most of the good characters either died or stopped being interesting. It wasn’t until the last two or three episodes where the show actually started to get good again, just in time for the finale.
“All in the Family,” after Rob Reiner and Sally Struthers left, and Danielle Brisebois came on board. That year, they also stopped taping in front of a studio audience, and the show lost every last bit of spark it ever had.
And then, of course, it stumbled forward as Archie Bunker’s Place for like 4 more years.
I don’t think Happy Days really collapsed, by this I mean the show seemingly loses it’s sense of direction and the writers/producers are just keeping it on the air to try to build up some more episodes to syndicate.
For instance I don’t think Kate & Allie collapsed at the end, but it just wasn’t funny. The whole show had been Kate was self assured and confident and Allie was building her self up slowly. Now all of a sudden, the roles reversed when Allie got married and moved out. The new roles just didn’t fit, but it didn’t seem to collapse and just lose direction. To me it just wasn’t as good.
Again I realize it’s just an opinion.
That’s why I am unsure of Roseanne, since Roseanne was going for an idea it wasn’t a real collapse but a planned change of direction that wasn’t as good.
Laverne and Shirley on the other hand had too many people just up and quit, and Drew Carey had contracts to play out, even though no one from the network to the actors seemed to want to be there; so that had a hand in why the whole show fell apart
Mork & Mindy.
IIRC, ABC was forced to film the last season as a contractual obligation. With it being the last season, the people making it decided to go mad a bit.
The main problem, however, was ABC airing the shows out of order. That led to some head scratching moments.
If I may be geeky, when the original Doctor Who was being show on PBS back in the 80’s, I loved that show, up until the last two Doctors. I know that Collin Baker’s character started abrasive on purpose, and was supposed to mellow out, but never got the chance, but Sylvester McCoy’s doctor… I don’t know. I thought the plots for each episode were stupid, and I never felt much of a sense of danger. Even though all the viewers know he’ll triumph in the end, the fact that he always seem to know that too just rubbed me the wrong way for some reason.
“Moonlighting.”
Rarely has such a delightful. original show ended so horribly. Everything that could go wrong after Cybill Shepherd’s pregnancy did.
One of the finest shows that just cratered out comes back this week - ER…
We’ll see how badly this ends, and I am not hopeful for a fine ending 
I really like Twin Peaks, but I do have to concede that it “collapsed” at the end simply because of
The bank vault scene in the last episode. Nothing like a nice big explosion of 4-5 main characters to help tidy things up.
THE SIMPSONS
“The end” will be starting its 7th season.
I’m with you all the way on X-Files, but I seem to be one of the few people that loved Twin Peaks all the way to the end. I really liked where they were taking the show, the only thing wrong was that they didn’t get the chance to do it the way they wanted.
edit: reading through the thread, I agree pretty much with what HPL said.
They should have quit after Dr. Green died. It’s been limping painfully ever since.
I would be more generous and say season 14 or 15, but I have no interest in watching the show any more.
While we are at it, I nominate My Name is Earl. I loved the first few seasons, but the “Earl in prison” plotline was too much. I removed it from my Tivo about halfway through this past season.
I agree with this. Recently I was watching the first few seasons on DVd, and okay, the 80s fashion are a bit much, but the show was really good, and I think still stands up very well. The Atomic Shakespeare episode still makes me laugh.
34 posts and no one mentioned the original Star Trek???
Twin Peaks started getting good near the end, but James’ affair with the married woman & the Lucy-Andy-Guy triangle just SUCKED, and that suckitude was stronger than Windom Earle & Dale’s being caught in the Red Room.
How’s Annie?
Newsradio still had some funny story arcs and episodes after the death of Phil Hartman. Patrick Waurburton playing Jimmy James’ nemesis was hilarious. I don’t think the show went to hell at all because it remained consistently funny.
Marc
The original series of Battlestar Galactica. It seems slightly camp and early 80s nowadays but it entertained me as a kid until suddenly the main characters were gone and they found the Earth. Suddenly it became pointless.
Ally McBeal just became totally desperate in the last few issues. Suddenly we had partnership, a half-daughter, a massive gap when the main character leaves, and the ghost of her ex. Utterly bewildering.
The first series of Beverley Hills 90210 started meandering after, first, Brenda lost her virginity in the famous “bang heard round the world”, and second, the main characters drifted away.
The supreme emperor of these has got to be Sanford & Son. What do you do when both of the title characters leave the show? We’ll show those prima-donna stars they can’t hold out for a better contract! Let’s rename the show and rebuild it around a cast of walk-on characters who’ve previously appeared. The Sanford Arms? Why it’s gold baby, GOLD!
I disagree. I thought Drew Carey worked toward righting all the wrongs of the previous couple of seasons and brought the show back to the core of Drew, his friends Lewis and Oswald, and Drew’s love life. He had a new girlfriend he was committed to (O.K., maybe Kelli was more or less a replacement for Kate, but the relationship seemed right.). With Mr. Wick’s help, he got the department store reopened. Sure, Wick took it over. He ended up back at his old job with Mimi sitting across from him calling him “Pig.” But even that felt right. And in the end he ended up a married man with a son. The series ended up on a happy note (Drew playing pool in the rain) and the whole final season felt right. Even with the KISS casket fiasco at his father’s funeral.