Seasonal Rot

"Seasonal Rot" is a popular phrase used in pop-culture for any long running show that experiences from a gradual drop in quality after several seasons, to either later becoming really bad or not as good as originally and before, even though the show can still make good episodes and stories, even if they are gone from grace, or just not make as much good episodes and make more duds/bad episodes and stories as possible.

Background
There are many great shows now and again. However, if a show runs long enough, Seasonal Rot always sets in and writers should always think of the right moment to either end the show (good way or bad way) or bring it back on track while it's still good, or the show can just start a new writing team to improve the series and make everything better in future.

Sometimes it's a temporary dip from which the series recovers by bringing in new writers (ones that either hardly know anything about the source material at all, or are very bad) or make the choice by ignoring all of the past events of the inferior or best seasons. Other times, it can be irreversible and grows with each new season at the point when the series has "jumped the shark" or lost its charm.

This includes Flanderization of really lovable characters (characters becoming out of character), make a few or a heck-load of filler/bad episodes, animation changes (even though, the animation would still be good, but could also turn to the ugly), come up with really stupid and inexcusable plots, take gross-out jokes gone horribly wrong, make the characters take a step too far, make episodes that don't even try, drag on everything for far too long, overuse the unfunny/poor comedy and jokes, make up poor attempts to go in a new direction and declining production values, throw in the three strike formulas used in every episode to make it a bad episode as possible, make the characters never learn their lesson, and also make the episodes use the same story repeated every episode.

There are some ways to avoid (or end) seasonal rot. One way is to temporarily postpone the series and come up with more ideas at a slow pace, keep the show as fresh and strong as possible, or just come up with new inspirations.

Making a Seasonal Rot worse is if the creator of the show is still heavily involved.

Notable Offenders

 * The Simpsons (Season 11—present; 1999—present - became the longest decline for any television series. Although not as bad as Family Guy in Seasons 7-present, the later episodes are hit and miss.)
 * Pokémon (Seasons 14-16; 2010-2012 - See what the problems are with Black and White by clicking on the link right here.)
 * The Fairly OddParents (Season 9—10; 2013—2017 - Season 9 introduced Sparky, but due to negative reception, he was removed without explanation, but was replaced with yet another new character: Chloe Charmichael, who was even worse.)
 * SpongeBob SquarePants (Season 6-8; 2008—2012 - The show has redeemed itself and improved since season nine and especially the post-sequel era.)
 * Family Guy (Season 7—present; 2008—present)
 * The Office (Season 8—9; 2011—2013)
 * Fireman Sam (Season 6-present; 2008-present - The show went completely downhill after the change from stop-motion animation to CGI.)
 * Thomas & Friends (Seasons 12-16, 22-24 (CGI animated runs of the original series); 2008-2012, and 2018-2020 - Season 12 was when the rot really started to kick in and go out of control with formulaic stories, plenty of bad episodes and flanderization of characters.
 * Two and a Half Men (Season 9—12; 2011—2015, Following Charlie Sheen's meltdown, The series replaced him with Ashton Kutcher, this aged badly with fans of the first 8 Seasons.)
 * Oggy and the Cockroaches (Season 4—6; 2012—2018)
 * Johnny Test (Season 4—6; 2009—2014 - Went downhill during the Cartoon Network Era. Similar to SpongeBob, the upcoming seventh and eighth seasons are looking to be improvements.)
 * Total Drama (Total Drama All-Stars & Total DramaRama; 2014, 2018-present)
 * Dexter's Laboratory (Season 3—4; 2001—2003 - Continued after Ego Trip, which sounded like a good series finale)
 * The Powerpuff Girls (Season 5—6; 2003—2005 - Continued after the departure of creator Craig McCracken)
 * LEGO Ninjago (Season 7, 10-11; 2017-2019)
 * Ed, Edd n Eddy (Season 5—6; 2005—2008 - Season 5 was okay, but Season 6 was short to two episodes without a reason or rhyme.)
 * Johnny Bravo (Season 4; 2004)
 * The Boondocks (Season 4; 2014)
 * The Grim Adventures of Billy and Mandy (Season 5-6; 2005-2007)
 * Game of Thrones (Season 7–8; 2017–2019)
 * Cheers (Season 11; 1992—1993)
 * Danny Phantom (Season 3; 2006-2007, Another Victim of Executive Meddling)
 * Teenage Mutant Ninja Turtles (2003) (Season 6-7; 2006-2009, Abandoned the Dark Tone that the Series had in the First 5 Seasons, However Turtles Forver did end the Series on a Proper Conclusion.)
 * Teenage Mutant Ninja Turtles (1987) (Season 8-10; 1994-1996, In Season 8, the show attempted to be edgy and dark, rather than the shows usual comedic tone. The series worsened in Season 9 with the removal of Shredder and Krang with replacements of both Carter and Lord Dregg. This is considered the moment when the series jumped the shark.)
 * Winx Club (Season 5-8) (When being revived by Nickelodeon, fans didn't take kindly to these seasons.)
 * The Price is Right (Season 18; 1989—1990, and season 31—audition period of 39; 2002—2011)
 * Looney Tunes (1933—1935, 1962—‎1969)
 * Tom and Jerry (1955-1958, 1961-1962)
 * Saturday Night Live (Seasons 6; 11; 20; 1980-1981; 1985-1986; 1994-1995)
 * Who Wants to Be a Millionaire? (Seasons 7—17 of the US syndicated version; 2008—2019, and series 22—30 of the UK version; 2007—2014)
 * Betty Boop (1934–1939)
 * Popeye The Sailor (theatrical cartoons) (1949-1957)
 * The Pink Panther (1978-1980)
 * The Loud House (Season 5-present; 2020-present, Major Flanderization of characters like Lincoln and Leni Loud.)
 * Bunk'd (Season 3–present; 2018–present; Seasons 3-5 removed several characters, and replaced them with new, unnecessary characters.)
 * The Ren & Stimpy Show (Season 3-5, Adult Party Cartoon; 1993-1996, 2003, The show went downhill in the Games Animation era (1993-1996) after John Kricfalusi got fired from Nickelodeon for infamous things in 1992 and Bob Camp replacing him in the control of the series as creative director and supervising director. Due to this, the show suffers from more restricted animation and less clever plots and writing, as well as spawning some horrible episodes.)
 * SML (Season 8-present; 2016-present) - After Jeffy was introduced to the series, he became one of the most overused characters and caused the downhill of what was once a decent web series.
 * Super Sentai (Season 11 of Showa Era; Hikari Sentai Maskman 1987-1988; Season 13-14, Season 19, Season 22, Season 25, and Seasons 37-39 of Heisei Era; Kousoku Sentai Turboranger 1989-1990; Chikyuu Sentai Fiveman 1990-1991; Chouriki Sentai Ohranger 1995-1996; Seijuu Sentai Gingaman 1998-1999; Hyakujuu Sentai Gaoranger 2001-2002; Zyuden Sentai Kyoryuger 2013-2014; Ressha Sentai ToQger 2014-2015; Shuriken Sentai Ninninger 2015-2016)
 * Star vs. the Forces of Evil (Season 3-4; 2017-2019, The show started to focus too much on the romance drama, the fantastical racism against monsters in Mewni became the series’ new main plot just suddenly, a bit right after Toffee’s death, without building up too much from the previous two seasons, and each episode had too many writers working on it, result few both old and new ideas becoming cut and mostly never used again, as pre-established in the first two seasons, as a result.)
 * Voltron: Legendary Defender (Season 7-8; 2018, Seasons 7 and 8 were not well-received by audiences mainly due to Shiro's boyfriend, Adam getting killed off in season 7. It wasn't even a dignified death, he died to prove how inferior earth tech is compared to the Galra.)

Minor
These are the ones that are nowhere even bad enough to deserve a page here.


 * Archer (Season 8—9; 2017—2018, The Premise of Archer falling into a coma wasn't to well received by fans)
 * The Big Bang Theory (Season 4—12; 2010—2019)
 * King of the Hill (Season 9—13; 2004—2010)
 * Dragon Ball Z (Season 7—9; 1993—1996)
 * Thomas & Friends (Seasons 8-11 (live-action run of the original series; 2004-2008), Season 8 introduced a retool for the series after HiT bought the show. Although, Seasons 8-11 aren't too bad, but they have their share of problems, inconsistencies, out of character acts, inaccuracies, and some bad episodes here and there like "Edward Strikes Out". (Seasons 22-24) The show declined in quality a little bit once again in Season 22 with another retool known as "Big World! Big Adventures" (though not as bad as S12-16, but is still a mixed bag like Seasons 8-11), and while that era had good (or watchable) episodes, and good portrayals of characters (like Thomas; most of the time). There are occasional problems here and there (i.e. the fantasy sequences, while creative despite how cartoony they look, can get distracting like the chasis bouncing at times, Season 24 (the final season of the original 1984-2020 run) toned them down a bit, showcasing some improvement. "Thomas and the Royal Engine" however was lucky to be the last episode in production order, ending the 1984-2020 series on a slightly higher note.)
 * Naruto (2005-2007)
 * Teenage Mutant Ninja Turtles (2012, Season 5)
 * The Real Ghostbusters (Season 3—7; 1987—1991)
 * Happy Days (Hollywood Part 3-Fonzie's Spots; 1977-1984; trope namer.)
 * Family Feud (1992—2006)
 * Wheel of Fortune (Season 21—present of the syndicated version; 2003—present)
 * Woody Woodpecker (1962–1972)
 * Doctor Who (Season 22—24 of the classic series; 1985—1987, and seasons 6—8 and 10—present of the relaunch series; 2011—2014, 2017—present)
 * Danger Mouse (2015) (Series 2; 2017-2019)
 * SMG4 Series (Season 9-present; 2019-present; Not bad enough to deserve a page, but unlike SuperMarioLogan, he still cares about his fans and as well as his work)
 * SML (Season 6-7; 2014-2015)
 * Gladiators (Series 5-7; 1996-1998)
 * GamesMaster (Series 5-7; 1995-1998)
 * The Loud House (Season 4; 2019-2020)
 * SpongeBob SquarePants (Seasons 4-5; 9a; 2005-2009; 2012-2014)
 * Angry Birds Toons (Seasons 2-3; 2014-2016)
 * Grojband (second half of Season 1, 2014-2015, until it ended with "Hear Us Rock", a 2-part series finale)
 * Jeopardy! (Season 18-present; 2001-present; the Clue Crew made their debut in Season 18)
 * The Fairly OddParents (Seasons 6-8; 2008-2012; while there were stinkers, these three are generally the last three good seasons before all hell broke loose starting Season 9)
 * The Simpsons (Seasons 9-10; 1997-1999; The infamous episode "The Principal and the Pauper", it led many fans to believe that The Simpsons went downhill after this episode, however despite this episode, these seasons are still good and many fans still consider these seasons the "Golden Age" for the show.)
 * Saturday Night Live (Seasons 28; 30; 33; 35; 38; 39; 44-present; 2002-2003; 2004-2005; 2007-2008; 2009-2010; 2012-2013; 2013-2014; 2019-present)
 * Pokémon (Seasons 20-22; 2016-2019; Sun and Moon was not at all that bad enough to deserve a page here to begin with, even if reception on the Sun and Moon run was divisive among fans and even if it had a laid back slice-of-life tone (which slice-of-life has been common since the show's beginning), it however gained critical praise over the years. Especially when Sun and Moon was the same era when Ash finally won a regional champion league after 22 years of failure to win, and met Brock and Misty again after Brock parted ways from Ash after Season 13 in the Season 20 two part arc finale, and again in Season 22.)
 * Turma da Mônica (Seasons 6-present; 2009-present)
 * Rugrats (Seasons 7-9; 2001-2004)
 * The Angry Beavers (Season 4; 2000-2001)
 * Sesame Street (Season 33-present; 2002-present)
 * ChuckleVision (Series 18-21; 2006-2009)