The Sopranos was voted to have never jumped and I agree. There were some weak episodes and one bad storyline (yes, Johnnycakes), but the overall arc stayed strong throughout.
How about Breaking Bad? It isn’t over yet of course, but as this is the last season, chances of shark-jumping seem remote. Though they could conceivably suffer from “last episode fizzle”. 
I could agree to that. And The Prisoner is the best and most venerable example of the trope. Although I could also get behind another phrase that was more Prisoner related. I just can’t think of one off hand.
Popped the security bubble? Became an irrational number? Launched the rocket of WTF?
Interesting post.
In literature, the best example I can think of for this is the Dark Tower series.
The best counter-examples, that is works filled with wierdness that do not end in a ‘painted into corner’ type fizzle, tend to be cases in which the structure of the narrative itself imposes some sort of pattern on the wierdness (Calvino’s If on a winter’s night a traveller or Mitchell’s Cloud Atlas).
The X-Files jumped no later than when they replaced both leads.
*Just Shoot Me *ran for seven seasons and I thought it stayed pretty consistent throughout.
Star Trek TNG Grew a Beard.
Looks like John DiFool beat me to the punch.
Carry on everyone, nothing to see here.
I would recommend then the following Shows:
Babylon 5
I know, I know. The show was slow to start but got progressively better and by the end it had a full grown beard. Eh… I do like that turn of phrase.
Battleship Galactica (2005)
Doctor Who (2005)
Though I am still unsure about current season. 50/50 depending on second part that is restarting soon.
It may strain the definition of “long running” but The Wire lasted four seasons without jumping.
I think most shows that make it that far start to show their age around season 5 or so. That is usually when the people behind it start moving on to other things and the people that take their place start making short cuts.
Sincs The Prisoner was only 17 episodes, I don’t think it qualifies as “long-running”.
Cheers? That went into the toilet big time when Shelley Long left. Not a fan of her or the character (or the “Sam and Diane” thing), but something happened to the show after that. The writing went downhill. People were just going thru the motions. The plots got really idiotic.
Plus Kirstie Alley is one of the world’s worst actresses.
For example, Tom Skerritt is a fairly good actor. It was painful to watch him walk thru his episodes.
Do shows ever even get the chance to Grow the Beard? It seems like they usually end up getting cancelled before the first signs of stubble.
Yeah, but it was Just Shoot Me. It consistently sucked from Episode 1 right through to the end.
Since it ran for 5 seasons, does that mean you think it jumped it after the fourth?
Though season 5 of The Wire was easily the weakest, I don’t think it ever jumped. I’ll also second Deadwood and The Shield.
Though they’re still running, I’d be surprised if Breaking Bad, Mad Men or Curb Your Enthusiasm ended up jumping the shark.
What, you missed the episode with Slow Donnie?
Monty Python’s Flying Circus.
Agreed…Brimstone is an excellent example-we’ll never know what the revelation in the final episode would have wrought down the road, because Fox then canceled it.
Ash, the putative lady cop, was actually an escapee of Hell, the ringleader of the escape in fact. Up to that point she had been making buddy-buddy with Zach.
Gunsmoke
I’d have preferred a restrained golf clap…but I tip my hat to your effort, my good fellow.