Fist of Doom Jr

Wow, that's a lot more than 3 seasons.

I'll vote for How I Met Your Mother.

stvn1974

The X-Files after season seven.

JeremyM

The Andy Griffith Show after Don Knotts left and it aired in color (the last 3 seasons).

Coral

All Showtime series that run 6 or more seasons?

sleepyhead55

I haven't watched the reboot yet so only commenting on the original series. You could just watch the first four seasons and skip the rest of the years. Five is ok to me but Emmy winning stuff compared to the next 3 seasons. 6 and 8 are awful and unwatchable. And 7 is only tolerable because of the two guest stars.

Damfino

Heroes

All downhill after first season.

Shannon Nutt

I should add that BILLIONS certainly seems heading here...ever since Damian Lewis was replaced by Corey Stoll (who is a good actor, but just not right for this series).

Nesbit

Feel like there’s a part of my soul still finishing some extended 6th season episode of Sons of Anarchy.

Fuck that show took a dip.

Mike86

New Blood deceptively got my hopes up for a better conclusion to the character/series. Some good moments sure, but all in all not very good and arguably a less satisfying series finale.

Toby Dramit

Dexter and True Blood were the first to come to mind for me. I agree with Mike86 that season 4 of Dexter was the last great one and that 5 was still pretty enjoyable. The first half of 7 was a nice return to form, I thought, but seasons 6 & 8 were a kick in the pills for those of us who watched this show from the beginning. There was just no excuse for writing that poor. Such a shame. The first 2 seasons of True Blood were/are fantastic but the cracks in the writing began to show in season 3. It became a parody of itself after that. Again, such a shame for two fantastic shows to end up the way they did.