But I do not mean the "One season, and then canceled" sense. I want shows that lasted beyond a single year, but only had one good season and then just totally tanked in quality afterwards.

Obviously the increasingly dreadful Community is one example, although, being only in season two, it could recover.

Twin Peaks
Desperate Housewives
Glee was only good for like seven episodes of one season but I don't think thats long enough to count
I'm also tempted to say Veronica Mars, which never reached the glorious highs of season one, but season two was satisfactory, I guess.

I can't remember many right now but I know there's a bunch.

wow

i wholeheartedly agree

FNL

What a terrible thread.

But my answer to this is Heroes. Joan of Arcadia as well, to a lesser extent.

Heroes was a victim of an inept showrunner. He tried too hard as the show progressed, then tried even harder to return to its glory days in its later seasons, but the damage was irreparable. I believe it's known as "Chris Carter Syndrome".

Heroes definitely sprang to mind first. Not saying the first season was perfect, but compared to the later ones...

Maybe Damages or Carnivàle.

Nooooooooo. VM might not have had tight story as in the first season, but both season 2 and season 3 kicked ass out of most TV shows back then and now.

Glee is certainly a great candidate. This season has been all over the place with a few bright spots here and there, but not enough to redeem the whole season. There's still almost half a season to go, so it has a lot of room to improve but considering the last two episodes somehow I just doubt it will manage to become even remotely as good as in season 1.

I definitely agree with Heroes. The first season was pure fun. But season 2 was awful and it only got worse.

Heroes. That's a no brainer.

Las Vegas, it never reached the epicness of the first season.

Prison Break, I never even saw an episode, but it had to have sucked after they broke out.

Prison Break was like Lost. It was never as good as that first season, but the show evolved from its initial concept enough that later seasons weren't so bad at all.

I cannot believe people actually bring up Veronica Mars and FNL

Obviously Heroes and Prison Break. Twin Peaks. Possibly Chicago Hope and Picket Fence though I don't remember it that well. O.C. would be on that list if it hadn't be for that great final season.

Friday Night Lights rebounded, but that second season sucked sooooooo badly that anyone would have been more than justified in never watching again.

As such, I do not find its inclusion shocking.

The hell? Carnivàle's second season was wonderful.

Season 2 of Glee hasn't been great, but it's been better than the back half of Season 1.

Definitely HEROES.

Heroes season one sucked too though.

I got two episodes into FNL season two before quitting, never to return. Maybe it did rebound; I'll never know.

I'll count the first nine episode order of Glee as its one good season.

You mean the first 13? Those were all shot together, the back 9 were filmed after the hiatus and after the show started becoming big.

Heroes and Twin Peaks are the obvious examples.

Heroes wasn't great for a whole season though. It was great for a whole season minus the last 5 minutes. Seriously, there was a collective groan from everyone watching during the final minutes of the finale. Heroes was an awesome ride that initial season, I don't regret watching it then, and I'm glad I jumped off in season two before it fully derailed.

No mention of the OC? As with Heroes, it's not like it was an amazing show like Twin Peaks Seasons 1.33, but damn did it fall off hard

That's debatable. Many, myself included, thought the fourth and final season was just as good as the first.

That should've been a huge hint that Tim Kring and Co. had no idea what they were doing when they massively screwed up the Season 1 finale.

As for Season 4, I never watched the last six or so episodes. It was good, compared to the previous two seasons, but the damage was done.

Yeah, it shoulda been. I think I knew, but refused to believe. I wanted it to do well, to be good, because of how fun that initial season was. I didn't make it as far as you did, Season 2 killed my interest.

Lost and The Walking Dead for me.