Flanderization

Flanderization is a trope that refers to the act of taking a single trait from a character and exaggerating and amplifying it more and more over time until it completely consumes the character. Most always, the trait/action becomes completely outlandish and it becomes their defining characteristic. Sitcoms and other comedy shows are usually the ones to suffer from this, due to the writers doing anything they can to get a cheap laugh from the audience, even if it means sacrificing a character's personality. Either there are out of character personalities that are counted as against the characters we know and love, or there are personalities that will make you have no choice but to lose all of the respect you had for the characters.

Although, flanderization doesn't always make the characters turn out awful. Sometimes flanderization can make them funnier and likable. It depends on how the character is flanderized. This good side of flanderization is most noticeable in Thor from the MCU, who became a less serious and more badass hero.

Flanderization is especially common amongst works where the creator is not involved, with their replacement not understanding the nuances of the characters and what made them so good in the first place, even if the lore was explained to them or had seen the series when the creator was involved. It is also extremely common in fanfiction for similar reasons no matter how devoted a fan is.

The Simpsons, being the series which spawned this trope's very name, has this almost across the board. Over time, the series has, in many ways, become a symbol of this trope in its purest form.

In the topic of flanderization, the American animated sitcom King of the Hill is a notable example of a series that used flanderization. This series is known for giving flatter characters new aspects, then focusing on them, thus creating the sense of flanderization at the same time as they get mh:greatcharacters:character development.

Flanderization is to not be confused with character derailment, in which it involves a character's trait(s) being vastly different compared to what was previously shown.

Although rare, some characters have actually recovered from flanderization overtime, like The Simpsons characters, Batman (DCEU), Superman (DCEU), Ben Tennyson (2016), SpongeBob SquarePants (Seasons 6-8), Patrick Star (Season 7) and Gwen Tennyson (2016).

Notable Victims of Flanderization
NOTE: If highlighted in green, it is positive flanderization.
 * Ned Flanders (The Simpsons; the trope namer, went from merely enjoying going to church to being obsessively religious and overly nice, and then later an obnoxiously intolerant bigot who will lash out at anyone that doesn't support Christianity. However, he managed to improve twice in Seasons 13-15 and the from Season 32-onward.)
 * Moe Szyslak (The Simpsons; became the show's punching bag, even before he was the show's punching bag, he was the primary target of Bart's prank calls, among other things, either done in a funny way or not so funny way. However, he managed to improve twice from Seasons 13-15 and the Season 32-onward.)
 * Homer Simpson (The Simpsons; Seasons 16-30; became a selfish and sometimes crazy moron. However, he managed to improve from Season 31-onward.)
 * Marge Simpson (The Simpsons; turned into an overprotective mother who is no fun at all, which is completely against her character. This happens in episodes which are disliked by fans, considered boring, or just plain bad. However, she managed to improve twice from Seasons 13-15 and Season 32-onward.)
 * Bart Simpson (The Simpsons; turned into a borderline sociopathic jerk, though not as bad as Peter Griffin. However, he managed to improve twice from Season 13-15 and Season 32-onward.)
 * Lisa Simpson (The Simpsons; became a know-it-all Social Justice Warrior, which is way too against her character. However, she managed to improve twice from Seasons 13-15 and Season 32-onward.)
 * Maggie Simpson (The Simpsons; became a flawless Mary Sue, despite the fact that she is likable and cute. However, she managed to improve twice from Seasons 13-15 and Season 32-onward.)
 * Garfield (The Garfield Show; became an unlikable slob)
 * Jon Arbuckle (The Garfield Show; became an idiot)
 * Nermal (The Garfield Show; became a jerk)
 * Harry Potter (Harry Potter novels 5-7; became an unlikable jerk. However, it is justified, as it was actually a result of trauma caused by Cedric Diggory's death.)
 * Hermione Granger (Harry Potter novels 5-7; became an annoying Mary-Sue and as much of a jerk as Harry)
 * Peter Griffin (Family Guy; Season 8-present; became an insane, rude, hypocritical, selfish, psychopathic, and egotistical person)
 * Lois Griffin (Family Guy; Season 8-present; became a sex-crazed, abusive, and short-tempered wife)
 * Meg Griffin (Family Guy; Seasons 8-14; became a punching bag up until Season 14)
 * Chris Griffin (Family Guy; Season 8-present; became a complete idiot in the worst way possible; however, he still kept most of his charm)
 * Brian Griffin (Family Guy; Season 8-present; his entire personality now amounts to being a "liberal", and became a complete jerk and got even worse when he came back)
 * (Family Guy; went from a toddler with the mind of an evil genius to a toddler with the mind of a stereotypical gay guy, but later returned back to how he was. Depending on your view, however, you could see this as character development since Stewie is no longer evil and has changed his ways, making him more likeable).
 * Glenn Quagmire (Family Guy; Season 8-17; became not just a pervert, but an implied child molester, though he did redeem himself).
 * Cleveland Brown (The Cleveland Show (Seasons 1); Went from being a nice character, into just a black version of Peter Griffin, though he did redeem himself).
 * Stan Smith (American Dad!; Season 11-present; went from being a well-meaning father, into the American Dad version of Peter Griffin).
 * Roger Smith (American Dad!; Season 8-Present; went from being a hilarious into a sadistic character who enjoys murdering.
 * Robin (Teen Titans Go!); became a completely overbearing and severely mentally or psychologically ill dominant jerk.
 * Starfire (Teen Titans Go!); became a more child-like and immature teen who adds "the" in almost every sentence she says and it gets annoying really quickly. She also screams a lot that it sounds like a high-pitched anime girl in an English dub yelling at the top of her lungs.
 * Beast Boy (Teen Titans Go!); became into an immature, whiny, destructive, literal party-animal teenager and a lazy couch potato who barely gets up to do something simple.
 * Cyborg (Teen Titans Go!); became an annoying idiot, with his giraffe neck gag being annoying at times.
 * Ed (Ed, Edd n Eddy; Seasons 5-6; became an emotional, unrealistically simplified, too-dumb-to-live idiot, although he is still likable all things considered)
 * Edd (Ed, Edd n Eddy; Seasons 5-6; became a constantly complaining goody-two-shoes)
 * Eddy (Ed, Edd n Eddy; Seasons 5-6; became an unlikable violent maniac)
 * Jimmy (Ed, Edd n Eddy; Seasons 2-6; became a vengeful camp gay crybaby)
 * Jonny 2x4 (Ed, Edd n Eddy; Seasons 2-6; became an annoying loudmouth goofball and saboteur who can't act or function without Plank)
 * Superboy-Prime (Infinite Crisis); became an angry fanboy because his version of Earth was destroyed.
 * SpongeBob SquarePants (Spongebob Squarepants; Seasons 6-8; became an obnoxiously happy moronic idiot and a crybaby in some episodes. In season 9-onwards, however, he finally got better after years of complaints from fans and critics.)
 * Star (Spongebob Squarepants; Seasons 1b-5; 6-8; he suffered two flanderizations, one of which was good and the other was bad; he started out as a kind of dumb but fairly intelligent, but as Season 1 progressed, he became more stupid and immature and eventually his stupidity became his main, defining trait (This was good Flanderization that made him funnier and more memorable). Unfortunately, in Seasons 6-8, he had a second Flanderization (which wasn't a good one). He essentially became brain dead, with his actions becoming dangerous at times. He also became a selfish jerk. True, Patrick had his jerky and antagonistic moments in earlier seasons, but these moments pretty much became a major part of him in these seasons. Then, in Season 9 onwards, he finally got better after years of complaints from fans and critics)
 * Mr. Krabs (Spongebob Squarepants; Seasons 6-8; turned into an even bigger black-hearted and self-serving greedy monster who, in one episode, terrorized Plankton to the point where he attempted suicide (yes, seriously) and Mr. Krabs just brushed it off like it was nothing; his love for money also became over-exaggerated)
 * Timmy Turner (The Fairly OddParents Seasons 9-10; went from a tragic, yet goodhearted child who just wanted his life to be better to a spoiled brat who only cares about getting what he wants.)
 * Cosmo and Wanda (The Fairly OddParents Seasons 9-10; went from a cute and loveable fairy god couple with the former being simple-minded, yet charming and the latter being the intelligent, yet voice-of-reason into a generic idiotic husband and nagging wife stereotypes who shared an equal amount of stupidity and carelessness, while frequently losing their wands for what can only be described as plot contrivance.)
 * Mr. and Mrs. Turner (The Fairly OddParents; started out as busy and clueless but soon became extremely negligent parents who have hinted at times that they don't truly love Timmy, and see him as a burden. This was actually the plot catalyst in an episode with a parody of the late Steve Irwin, called 'The Bad Parent Hunter'. While their characterizations were never perfect from the start, they were more tolerable in the first five seasons aka the classic era. Mr. Turner, in particular, has worsen as the show went on, especially in the final two seasons, due to the "Idiot Dad" trope being severely overused on him similar to Cosmo and the fact that he acts like a complete child. Mr. Turner's screen time has also been unbelievably increased in the final two seasons, usually for humor's sake.)
 * Vicky (The Fairly OddParents Seasons 6-10; went from a sadistic bully who enjoys torturing Timmy while keeping him safe, to a psychotic killer who wants to outright kill Timmy for no apparent reason while also having a severe reduction in screen time despite still appearing in the intro of the show.)
 * Tootie (The Fairly OddParents Seasons 6-7; went from a nerdy, yet nice girl who has a crush on Timmy and occasionally helped him to an obsessive, lovesick stalker who constantly harasses Timmy whenever she sees him.)
 * Denzel Crocker (The Fairly OddParents Seasons 9-10; went from a crazed teacher wanting to prove the existence of fairies to the world into just another annoying manchild like what Mr. Turner has become as well as an incompetent and idiotic villain while being shoehorned into almost every episode, usually for humor's sake like Mr. Turner.)
 * Jorgen Von Strangle (The Fairly OddParents Seasons 9-10; started out as an intimidating and lawful antagonistic fairy ruler, but as the show went on, he got dialed down to being more of a supporting role. Depending on your view, you may find this as an actual development in character. However, at times, this also made him more of a wimp as evidenced in "Teeth for Two". Then by Season 9, he was dumbed down to just a generic plot device whenever the writers needed to bastardize Da Rules.)
 * Hank Hill (King of the Hill; is known for preferring traditional things over trendy new ones. This starts to get overdone in the later seasons; case in point, "Get Your Freak Off". In this episode, Hank is more Amish than the Amish; he's almost medieval)
 * The Annoying Orange (The High Fructose Adventures of Annoying Orange; became more annoying than he was in the web series to the point where he is not even funny)
 * Jamie (TAWOG Season 3)
 * Eric Cartman (South Park; became an absolute villain rather than just a jerk; not to mention, his bigotry used to be only targeted toward Kyle)
 * (South Park; became a very sweet boy, one of the few times a Flanderization made a character even more popular)
 * Wendy Testaburger (South Park; Becomes an irredeemable bitch who breaks up Stan and flirts millions of guys for no reason, when she tells all of the girls to gain war against boys over, which is racist. But one girl was killed like Mrs. Ellen for obbessesing Stan and unlikeable Social Justice Warrior towards their girls' and Butters's picture.)
 * Gerald Broflovski (South Park (Season 20); became a troll on the internet and drove a person to suicide and it doesn't help that he is a Karma Houdini in this Season.)
 * oo (Foster's Home for Imaginary Friends; started out as being protective over and caring of Mac in the pilot whilst being only slightly mischievous and then became a "jerk with a heart of gold" type of character in the first season, but then eventually he lost the "heart of gold" part and just became a full-blown, straight-up, outright meanie whose jerkiness kept getting worse and worse as the show went on until he finally started leveling off around the end of the series)
 * Earl Devereaux (Cloudy with a Chance of Meatballs; became a rude and manipulative jerk in the TV show adaption)
 * Mater (Cars; became an idiot jerk in the second film, until his flandzerization is undone in Cars 3)
 * Optimus Prime (Became a psychotic killing machine in Transformers 2: Revenge of the Fallen)
 * Ren Hoek (Ren and Stimpy: Adult Party Cartoon; same as Optimus Prime)
 * Son Goku (Dragon Ball GT and Super; became dumber and more of a manchild)
 * Chi-Chi (Dragon Ball Z, GT and Super; became an obnoxiously overbearing mother to her sons, Gohan and Goten, to the point where she attempted to take Gohan's infant daughter away from him as she couldn't stand the thought of her becoming a Z-Fighter when she grew up)
 * Broly (Dragon Ball Z: Broly - Second Coming; became a brainless lunatic who did nothing but scream "KAKAROT!" at the top of his lungs)
 * Miho Nosaka (Yu-Gi-Oh! 1998; became a selfish, hypocritical ditz who uncaringly strings Honda around when she clearly has no interest in him and just uses him for her own personal gain)
 * Sakura Haruno (Naruto; became a violent psychopath who often attacks Naruto for no apparent reason)
 * Sheen Estevez (Planet Sheen; Went from being a funny comic relief to an immature, childish, and unfunny idiot)
 * Spike Bulldog (The Tom and Jerry Show; went from being a friend to Jerry in the original, theatrical shorts to a mean-spirited, short-tempered jerk who hates and bullies both Tom and Jerry)
 * Tommy Oliver (Power Rangers; became an annoying ranger every season after season)
 * Manny the Mammoth (Ice Age; became a stereotypical over-caring father in Ice Age 4: Continental Drift and became dumber and dumber as films went on.)
 * Sid the Sloth (Ice Age; Became a stereotypical lazy bum in Ice Age 4: Continental Drift and became dumber and dumber as films went on.)
 * Max Russo (Seasons 3-4) changed from a funny, laid-back, and yet, kind-hearted and dimwitted character with slight intelligence, to an annoying, aggravating, arrogant, jerky, and a too dumb to live-type character, who's only there for comedic purposes, much like Patrick Star from Seasons 6-8 of SpongeBob SquarePants.
 * Red (Angry Birds Toons; Season 2-3; because an overprotective Gary-Stu angry bullylike jerk that likes beating the innocent pigs for fun and leaving them to starve. He is also very racist towards the pigs and is very mean to them for no real reason)
 * Chuck (Angry Birds Toons Seasons 2-3; Changed from a lovable, funny speed demon to an annoying idiotic jerk who cares more about looking cool than protecting the eggs, he also gets too much screen time in the newer seasons.
 * Jim, Jake, And Jay, (The Blues From Angry Birds Toons; Seasons 2-3; became annoying troublemaking brats that also like to beat the pigs for fun.)
 * Matilda (Angry Birds Toons; Season 2-3; Became an OCD overprotective Neat Freak that wants everything to be perfect.)
 * Bomb (Angry Birds Toons; Seasons 2-3; Became a boring loon with no personality and eats ice cream for no reason.)
 * The Pigs (Angry Birds Toons; Seasons 2-3; Became a 1-dimensional villain characters who want to steal the eggs from the Birds for no real reason when they could’ve eaten something else, and they also became punching bags for the Birds.)
 * Jungho (The Devil's Boy; Season 2-3); Became a more psychotic, unheroic, vengeful bullied boy after her crush, Lee Yoonhee commited suicide.
 * John Doe (UnOrdinary; 2nd half of Season 1, Season 2); Became an arrogant, unheroic bullied teenager, who grew tired of being crippled by his tormentors.
 * Dongtae (DICE: The Dice That Changes Everything; season 4)
 * Pencil (BFB) (Battle For BFDI; became a mean unlikable leader)
 * Leafy (Battle For BFDI; became a ungrateful mary sue who damages her relationship with Firey. Fortunately, Leafy apologized to Firey in BFB 22)
 * Firey (Battle For BFDI; became a selfish Gary Stu who thinks that Leafy stole Dream island, but is still well received by fans)
 * Book (Battle For BFDI; became an unlikable jerk to Taco)
 * Foldy (Battle For BFDI; became a bland Mary Sue who, in BFB 11, made Iance lose all because Stapy was eliminated)
 * Paintbrush (Inanimate Insanity Season 2; went from a responsible contestant who is pragmatic in their approach to challenges and life to an overly competitive, impatient, bossy, and short tempered jerk who often takes things WAY too seriously. The way they treat Fan in episodes like Mazed and Confused and the second part of Kick the Bucket also possibly hints that they often overwork any member of the Bright Lights whenever they slack off)
 * Nickel (Inanimate Insanity II; went from a critical character to a selfish and egoistical jerk that made Suitcase paranoid and tried to break up Suitcase and Balloon)
 * Lego (Object Invasion; Episode 6-onward; he went from a kind, yet self conscious friend of Cup to a bossy leader who gets angry when his team loses, and he once blamed his own team for losing the challenge, and doesn't care about whatever gets in his way, which led to his elimination)
 * Greg Heffley (Diary of a Wimpy Kid: The Long Haul (film) became an idiot.
 * Frank Heffley (Diary of a Wimpy Kid: The Long Haul (film) is the same as Greg.
 * Susan Heffley (Diary of a Wimpy Kid: The Long Haul (film) became a selfish and egotistical mother who belittles her family and bashes modern technology. She can also be an idiot at times like Greg and Frank.
 * Andy Bernard (The Office (US): Seasons 8 and 9; became very annoying.)
 * Puckett (iCarly Seasons 4-5; Sam & Cat); Was flanderized twice (first one was good, second one was bad). In the earlier seasons of iCarly, she started out as being an aggressive tomboy. During Seasons 4-5, however, she became somewhat less aggressive and more girly (this was good Flanderization that made her more lovable and memorable). Then, during Sam & Cat, she became a selfish jerk (which unfortunately, was a bad flanderization rather than a good one).
 * Cat Valentine (Victorious Post Season 2, Sam & Cat) became even dumber than she was in the first 2 seasons of Victorious to the point of being an absolute idiot.
 * Sam Wilson/Falcon (Marvel Comics; became out of character after becoming the "new" Captain America)
 * Mark Taylor (Home Improvement; Season 7; became a gothic weirdo.)
 * Agent 3 (Splatoon); Started out as the hero you play who defeated Octarains because they stole the Great Zapfish, to a heartless racist jerk who attacked Agent 8 simply because he/she was an Octoling and Octolings used to be the bad guys in Splatoon, even though this Octoling became good due to hearing the Calamari Inkantation and wouldn't attack Agent 3, yet Agent 3 still wants to attack Agent 8 because they were an "evil" Octoling. Thankfully, Agent 3 became good in Octo Expansion because he/she saved Agent 8 and Cap'n Cuttlefish from being blended alive and was nice to Agent 8 and realized that not all Octolings are bad guys.)
 * Wonder Woman (2011); Became a selfish, cold-hearted and murderous bully.
 * Superman (DCEU); Became an eternally depressed grump who almost never smiles and a boring Jesus allegory.
 * Lex Luthor (DC Extended Universe); Became a spoiled daddy’s boy who acts like a wacky cartoon character.
 * Joker (DC Extended Universe); Become a generic edgy gangster wannabe with tattoos and silver teeth.
 * Lois Lane (DC Super Hero Girls (2019)); Became a manipulating freak and Mary Sue clone of Courtney who once followed the Superhero Girls around to prevent them from protecting Metropolis from the Killer Moths, resulting in the city being attacked by them.)
 * Luke Skywalker (Star Wars: The Last Jedi); became a cowardly old grump who nearly refused to train Rey.
 * Blossom, Bubbles, and Buttercup (The Powerpuff Girls (2016)); (Blossom became a neurotic geek, Bubbles became one of the girliest girls while still retaining some of her more psychotic episodes, and Buttercup became a bully).
 * Jerry (Gene Deitch Version); Went from being a troublesome and cunning, but cute, funny, and loveable mouse to a flat-out sadistic jerk who enjoys torturing Tom for fun and even makes Tom's owner torture him even more. Luckily, he redeemed himself in the Chuck Jones-era.
 * Daffy Duck (DePatie Freleng/Seven-Arts era); went from a mischevious screwball prankster into a grouchy, humorless sadist who heavily disregards others in favor of getting what he wants and inflicts abuse on innocent characters such as Speedy Gonzales).
 * Eustace Bagge (Courage the Cowardly Dog in Ball of Revenge); Became a murderous jerk who wants Courage dead because he gets all the attention from Muriel.
 * Will Schuester (Glee Season 4-5); Became a stubborn, obsessive and pushy manchild.
 * Rachel Berry (Glee Season 2); Became a complete psychopath who never does something without an ulterior motive of stardom.
 * Tina Cohen-Chang (Glee Season 4-5); Became an unlikable diva.
 * Blaine Anderson (Glee Season 3-5); Became an immature manchild.
 * Sam Evans (Glee Season 4-6); Became dumb as a rock, to the point where he was barely functional.
 * Buddy Thunderstruck (Get the Hock Out and Cannonballistic; became dumber and more immature than he was in the previous episodes, since he usually does stupid things, often gets himself in trouble, doesn't listen to other people, and acts like he doesn't care for the bad things that happen to them or even himself to the point of him never getting told off or punished for his mean-spirited and stupid actions).
 * Artichoke (Buddy Thunderstruck in Get the Hock Out; became a stereotypical Edgelord who only threatens to kill other people when he gets distracted or someone stole his motorcycle).
 * Auntie Uncle (Buddy Thunderstruck in Get the Hock Out]; became an extremely braindead and spoiled Mary Sue-typed party animal who only cares about losing Buddy's money to other people and even sold all of Buddy's furniture and even her own furniture to Big Tex just to "keep the business going" which could give post-movie Patrick Star or modern Peter Griffin a run for their money).
 * The Townspeople of Greasepit (Buddy Thunderstruck in Get the Hock Out; most of them (expect Muncie, Mama Possum's babies, the Beavers, Big Tex, and Artichoke) either became dumber than they were in the previous episodes, butt-monkeys or joke fodders who seemed to have lost all of their brain cells and never punish or call Sheriff Cannonball on Buddy and Darnell for their actions up to the point where they both got off scot-free).
 * Daenerys Targaryen (Game of Thrones Season 8 Part 2; Became a poorly written mad tyrant.)
 * Junko Enoshima (Danganronpa 3: The End of Hope's Peak High School; Went from a complex and cunning, yet entertaining antagonist with a detailed motivation and interesting personality filled with opportunities to talk and speculate about her to an incompetent, one-note "I'm going to destroy civilization because I'm evil!" Generic doomsday villain.)
 * Pac-Man (Pac-Man and the Ghostly Adventures; Went from a video game icon who turns out to be lovable towards many gamers into a glutton who focuses more on food rather than helping others.)
 * Earthworm Jim; Was a hilarious and memorable video game character who turned out to be quite lovable from the cartoon and towards many gamers because of the first two games, but Earthworm Jim 3D made him somewhat annoying, forgettable, and unfairly accident-prone.
 * Tyler Navarro ("Power Rangers Dino (Super) Charge"; became an idiot, an unlikable Red Ranger and one of the most annoying characters)
 * Riley Griffin ("Power Rangers Dino (Super) Charge"; became immature and only cares about winning.)
 * Koda ("Power Rangers Dino (Super) Charge"; became a silly comic relief in the second season)
 * Woody Woodpecker (Woody Woodpecker 2017; Became an unlikable sadist)
 * The Banana Splits (The Banana Splits Movie; Became murderous monsters)
 * Lanolin (Orson's Farm; Became a HUGE jerk towards everyone, especially Roy)
 * Mr. Goodman (SML; Went from an decent person to a money-loving, money-hungry jerk towards Mario)
 * Mario (SML; He went from a down to earth man living in a house full of idiots to a sometimes stupid yet stereotypical dad and a Butt-Monkey,but is still innocent and likable)
 * Bowser Junior (SML mid-late 2019-2020; Became extremely unlikable, overly annoying, unfunny, and dumb, and tortures Chef Pee Pee and Cody for no reason other than to entertain himself, though he is more likable in late 2020 onwards)
 * Joseph (SML 2017-2020); Became an unlikable character whose sole purpose is to be Bowser Junior's annoying Yes-Man, try to look cool and to be on the radical side of things (even if it is genuinely dangerous and questionable), and also became a greedy spoiled jerk on par with The Goodman Family in "Joseph the Millionaire!".
 * Rosalina (SML 2016-2017 & 2019-2020; Became an insensitive, excessively dull-witted, and nagging mother who yells at Mario and defends Jeffy for no good reason. Not even she was immune to Flanderization while she was the typical dumb blonde character as well)
 * Wreck-It Ralph (Ralph Breaks the Internet; became an immature and selfish jerk who lives to only have Vanellope by his side, even though he redeems himself towards the end)
 * Mushu (Mulan II; went from a funny comic relief to a self centered jerk for no reason.)
 * Hua Mulan (Mulan (2020); became a Mary Sue and physical fighter and was apparently born gifted.)
 * Kai (LEGO Ninjago: Masters of Spinjitsu; Seasons 8-12, went from a short-tempered, yet caring ninja to a whiny, narcissistic character.)
 * Jay (LEGO Ninjago: Masters of Spinjitzu; Seasons 8-onward; His timidness overtime evolved into just being utterly dim-witted)
 * Jeffy (SML 2016-now); While he was stupid & mostly annoying ever since his introduction into the SuperMarioLogan series, he has now become dumber, controversial & imbecilic for infamous reasons, manipulative at times, has become more of a cash cow for SML now, and he has also become a lot more obnoxious with his tediously excessive jokes being more exaggerated than before (so much that it makes Bowser Jr look harmless by comparison in some instances), and such to the point that there were some fans that wanted Logan to burn the Jeffy puppet.
 * Lloyd Montgomery Garmadon (LEGO Ninjago: Masters of Spinjitzu; Seasons 11-present; became more of a stereotypical leader in a kids' cartoon.)
 * Dareth (LEGO Ninjago: Masters of Spinjitzu; Seasons 8-present; became more of an attempted comic relief character than an actual comic relief character)
 * Susan and Mary Test (Johnny Test; Seasons 4-6, went from great partners in training with comedic traits and creative experiments, with safety precautions when testing on Johnny to having no problem experimenting on Johnny no matter how dangerous. More than half of those are for Gil. They are also hypocrites)
 * Bling-Bling Boy (Johnny Test; Seasons 4-6; became blander as a villain, while at the same time actually gaining character development)
 * Danger Mouse (Danger Mouse; Became a stereotypical hero who can often be very unlikable)
 * Penfold (Danger Mouse; Went from a humorous dim-witted coward to a stereotypical bland and gay coward)
 * (Danger Mouse; Season 5 (1981)-onward; Became a dumb yet likable colonel)
 * (Danger Mouse; Season 5 (1981)-onward; Went from a loyal henchman of Baron Greenback to a stupid henchman)
 * (Danger Mouse; Season 4 (1981)-Season 10 (1981); Season 1 (2015)-onward; Started off not having a problem, then started hating his job wanting to quit since the fourth seasons seventh episode Tower of Terror, saying he wanted to be on Radio 3. However, after the reboot he started tolerating his job more, being the comic relief character and a show-stealer, all while still being likable)
 * Jack Sullivan (The Last Kids on Earth; Became an unlikable idiot)
 * Fred Jones (Be Cool, Scooby-Doo!; Became even more obsessed with traps to the point it permanently damages his relationship with Daphne.)
 * Daphne Blake (BSCD; Became very stupid, to the point where it also damages her relationship with Fred.)
 * Velma Dinkley (BSCD; Became a know-it-all.)
 * Shaggy Rogers (BSCD; Also became very stupid, to the point where he is more stupid than cowardly)
 * Scooby-Doo (BSCD; Same as Shaggy)
 * Mrs Axzyte (Axzyte; Went from a mother who disliked games into an abusive mother)
 * The Days Union (ROBLOX; Went from being passive myths that are against The Night Coalition to being hostile and rabid myths)
 * JackCult (ROBLOX; Same as The Days Union, he went from a nice 14 year old child that was the only safe Cult Family myth to a hostile myth)
 * BrandonCult (ROBLOX; Went from a serious myth from a corrupt family to a user that looks unrecognizable and acts nothing like his past self, and also made a disgusting game where you literally eat poop.
 * Norman Price (Fireman Sam Season 6-Present; He went from a mischievous boy who likes to play tricks to a whiny, annoying brat who does horrible things for the pettiest reasons)
 * Elvis Cridlington (Fireman Sam Season 6-Present; He went from a not so bright but friendly firefighter to an incompetent idiot)
 * Scoop (Bob The Builder (2015 Reboot); He went from a sensible and reliable leader to a clumsy and careless goofball who messes everything up)
 * Lofty (Bob The Builder (2015 Reboot); He went from a friendly, shy coward to a sarcastic, cynical, intelligent crane who isn’t scared of anything anymore)
 * Muck (Bob The Builder (2015 Reboot); He went from being a funny but reliable vehicle, into an idiot who screws up like Scoop).
 * Tiny Kong (Donkey Kong; She went from a tough, small, and cute little girl who was able to shrink (hence her name), to a tall, sexual teenager, who has no personality.)
 * Lincoln Loud (The Loud House Season 4-Onwards; He became even more of a butt monkey and also became more selfish.)
 * Leni Loud (The Loud House; Became even dumber to the point she went to pre-school in Schooled.)
 * Baby Bop and BJ (Barney & Friends; in later seasons, Baby Bop can no longer count and the two constantly need help from Barney to learn)
 * Natsuki (DDLC: Loser MC; Became even more mean to MC)
 * Shadow The Hedgehog (Sonic Boom; went from a likable Anti-Hero to an unlikeable villain with no backstory)
 * Knuckles The Echidna (Sonic Boom; becomes an idiot tough guy)
 * Michelangelo (Teenage Mutant Ninja Turtles 2012; became even more of an annoying idiot in Season 5).
 * Big Bird (Sesame Street; Journey to Ernie made him a Steve Burns-like host)
 * Thomas the Tank Engine (Thomas & Friends; became an idiot who never pays attention and makes lots of mistakes between Seasons 12-16.)
 * Gordon the Big Engine (Thomas & Friends, Season 8-15); he was flanderized into becoming the Thomas & Friends version of Brian Griffin from Family Guy and acts like an arrogant jerk.)
 * Toby the Tram Engine (Thomas & Friends, Seasons 9-16; 2005-2012 He went from an old and wise engine into a paranoid wimp who is too scared to do anything.)
 * Edward the Blue Engine (Thomas & Friends, Seasons 11-16; Much like Toby, he went from an old and wise engine into a paranoid wimp who is too scared to do anything.)
 * Henry the Green Engine (Thomas & Friends, Seasons 12-19; He went from a kind and friendly gentle giant into a coward who constantly worries too much about every little thing and is too stupid to do anything right.)
 * Percy the Small Engine (Thomas & Friends, Seasons 15-16); Percy went from being a naive engine, into a a idiot, dimwit and a crybaby who obsesses over Thomas' attention.)
 * Emily the Stirling Engine (Thomas & Friends, Seasons 8-10, 12-16; She went from a kind and helpful engine to a bossy, naggy and selfish engine.)
 * Skarloey and Rheneas (Thomas & Friends, Seasons 9-12, They started out as kind and wise old engines into spoiled, immature brats who like to fight and argue over trains.)
 * Sir Topham Hatt(Thomas & Friends, season 19-24, went from a stern but fair father figure to the engines to a goofy idiot who acts more like a comic relief.)
 * Zoe (Sesame Street; became obsessed with ballet)
 * Blue (Blue's Clues; Blue's Room made her an annoying, overly-talkative dog)
 * Cookie Monster (Sesame Street; became an omnivore)
 * Yoshi (Yoshi Topsy-Turvy; lost his ability to make and throw eggs)
 * Chris McLean (Total Drama; Total Drama: Revenge of the Island onwards; became even more psychopathic later on in the series)
 * Courtney (Total Drama, Total Drama Action onwards; became more aggressive)
 * DJ (Total Drama, Total Drama World Tour; became a crybaby who complains about an "animal curse")
 * Gwen (Total Drama, Total Drama Action onwards; she was originally a moody and sarcastic yet kindhearted girl, but in "Action", her impulsive actions between her and Trent somewhat caused her to lose Trent as a boyfriend, and in "World Tour", she became more of a jerk, and while she did show some remorse for her kissing Duncan, and when everyone finds out about the kiss, she doesn't vote herself out or apologize, and she tried to manipulate Cody's feelings to vote Courtney off, and in "All-Stars", she became more girly)
 * Duncan (Total Drama, Total Drama World Tour onwards; in "World Tour", he became more of a jerk to the point of cheating on Courtney, and in "All-Stars", his soft side gets exaggerated to the point of where he can't stop himself from being nice)
 * Lindsay (Total Drama, Total Drama All-Stars; became even more stupid to the point where she couldn't push a cart)
 * Leshawna (Total Drama, Total Drama Action onwards; in "Action", she fake-cried to her teammates about going to the spa, and proceeded to trash-talk them afterwards, and in "World Tour", she became bossier and more rude to her team)
 * Owen (Total Drama, Total Drama Action; became more unfunny and obnoxious)
 * Sierra (Total Drama, Total Drama All-Stars; became more insane and imagines Cameron as Cody)
 * Zoey (Total Drama, Total Drama All-Stars; became a Mary-Sue and became dumber to the point she didn't realize Mike was Mal)
 * (Total Drama, Total Drama All-Stars; became dumber and more incompetent, though this is a good flanderization because it made him more likable and have more funny moments)
 * Geoff (Total Drama, Total Drama Action; he became more like Chris in the aftermaths)
 * Bridgette (Total Drama, Total Drama Action onwards; became more obsessed over Geoff, and in "World Tour", she couldn't control her hormones to the point where she cheats on him with Alejandro)
 * Trent (Total Drama, Total Drama Action; became obsessed with Gwen and the number 9)
 * Ezekiel (Total Drama, Total Drama World Tour onwards; became the Gollum of the series)
 * Cameron (Total Drama, Total Drama All-Stars; became more dumber, and didn't realize Mal exists even though Cameron is supposed to be one of the smartest characters in the series.)
 * Dave (Total Drama, Total Drama: Pahkitew Island (episode 6/7-onwards), became a crybaby who was obsessed with Sky, to the point where he voted himself out in episode 9, and in the finale, he went insane and tried to hurt Sky)
 * Sky (Total Drama, Total Drama: Pahkitew Island (episodes 9-ownards), became overly competitive to the point where she threw a childish temper tantrum in the finale)
 * Cody (Total Drama, Total Drama World Tour; Became somewhat hypocritical and a jerk, though this is minor, and can be seen as good by some people)
 * Sanji (One Piece, Went from a really cool guy who had a weakness for women into a perverted guy who always goes blood-losing every time he sees a girl)
 * Makoto Itou (School Days and Summer/Shiny Days, a cute shy guy who become an irredeemable jerk and a sexual predator.)
 * Johnny Bravo (Season 2-3) (Johnny Bravo, became as dumb as a bag of rocks.)
 * Silver The Hedgehog (Sonic: Super Genesis Wave; became a cruel jerk to Sonic and everyone.)
 * The Cat in the Hat (The Wubbulous World of Dr. Seuss; started out as a trickster, but in Season 2 he became more of a Bear in the Big Blue House-like host who, like Elmo from Sesame Street, gets way too much screen time)
 * Jenna (30 Rock; became an attention whore and a self-centered diva in Season 3)
 * Eric Matthews (Boy Meets World; became dumber and dumber as the show went on starting in Season 3 to the point where he was unable to put the right shoes on his feet)
 * Caillou (Caillou Gets Grounded; became an extremely unlikable, mean-spirited, callous, sociopathic and malicious jerk who takes pleasure in constantly causing trouble for no reason and making his family's and other's lives miserable. True, he was unlikable in the original PBS series because he was very bratty and often threw temper tantrums. However, he was nowhere near as unlikable as he is here. In fact, he is so unlikable in this series that he could give his original PBS counterpart a run for his money. However, his personality can sometimes vary since there is more than one user who makes the videos.)
 * Boris and Doris (Caillou Gets Grounded; became cruel and abusive parents towards Caillou who constantly ground him for ridiculously long periods of time for his bad behavior and sometimes even ground him for stupid and nonsensical reasons or for things that aren't that big a deal. They are especially abusive towards Caillou in the Punishment Day Videos because they give him over-the-top punishments. In fact, they can be just as bad as, if not sometimes even worse than Caillou. However, Doris is shown to be somewhat more caring towards Caillou than Boris. Boris also finds enjoyment of torturing his son for fun. They also abuse Caillou instead of punishing him. Doris even defended him on some occasions. Like Caillou, their personalities can sometimes vary since there is more than one user who makes the videos.)
 * Rosie (Caillou Gets Grounded; became a huge tattletale, Caillou's punching bag and a Mary Sue, although she is still a likable character compared to Caillou, Boris, Doris and the following two characters in Caillou Gets Grounded, which are Miss Martin and Dora. However, she can have some unlikability at times, such as by contributing to Caillou's over-the-top punishments in some of the Punishment Day Videos. Like Caillou, Boris and Doris, her personality can sometimes vary since there is more than one user who makes the videos.)
 * Miss Martin (Caillou Gets Grounded; became a stereotypical mean teacher towards Caillou who treats him in a similar way to how Boris and Doris treat him, except she is not his parent and she does not ground him. Like Caillou, Boris, Doris and Rosie, her personality can sometimes vary since there is more than one user who makes the videos. The only thing about her that's better than her original counterpart is her character design. Still, this does not excuse her flanderized personality.)
 * Dora (Caillou Gets Grounded; is the same as Caillou, except she was likable in the original Nick Jr. series and its sequel Dora and Friends: Into the City!. Like Caillou, Boris, Doris, Rosie and Miss Martin, her personality can sometimes vary since there is more than one user who makes the videos.)
 * Simba (The Lion Guard; A likeable and sympathetic hero who became an unlikeable and stereotypical overprotective and over-caring father towards both Kion and Kiara.)
 * Kiara (The Lion Guard; Became an arrogant and snobby brat.)
 * Nana (Elfen Lied; rather than improving to protect her family & friends, she becomes more of a pathetic damsel fighter in many later parts of the manga, where Kurama or Bando always save her & Mayu.)
 * Edward Elric (Fullmetal Alchemist (2017 film); becomes a pathetic stereotypical shounen anime protagonist who lacks the charm of the original Edward Elric)
 * Winry Rockbell (Fullmetal Alchemist (2017 film); she is turned into a stereotypical whiny damsel in distress who always needs saving from Edward Elric)
 * Bob Bobowski (SMG4 2018); (although he was always obnoxious, but they were done in a hilarious way, however in 2018, he became more unlikable where in "Mario and the T-Pose Virus", he got his friends turned into T-Pose Zombies, and in the "The Rapper Bob Arc", he made a nasty speech to Boopkins to the point where he made him cry, and in the same arc he became more of a jerk to the point of dissing his friends in a rap just to become more famous)
 * Axol (SMG4 late 2020-onwards); (he went from a kind and understanding manga artist to a simp who lusts over Melony no matter what)
 * SMG4 (SMG4 2017-onwards); (he went from being the straight-man with Mario's stupidity to becoming a stereotypical meme-loving addict)
 * Princess Peach (SMG4 2018-onwards); (she became much more bossy, rude, and selfish than her previous personality to the point where in "If Mario was In.. Fall Guys", she punished Mario after Mario gave King Bert, the original owner, the crown instead of her. This showed that she cared about herself, also in "Food Wars", she threatened to kill Mario and his friends for participating at the "party")
 * Toad (SMG4 season 2014-2015 & 2018-onwards)(he received two flanderizations; In the first three years, he went from a comedic, mistreated and a slightly grumpy and sarcastic helper, similar to Squidward Tentacles in Seasons 1-4 and Season 9-present of SpongeBob SquarePants. However, in 2014-2015 he became a crazily obsessed fan of Mario who is addicted to sugar and often played as a poor attempt at comic relief; a complete 180 from his original personality. He would later retain his original personality in the later years, but in 2018-present, he would later become a more grumpy person who would often serve as a punching bag who is heavily mistreated by Toadette (similar to Squidward in seasons 5-8 of SpongeBob SquarePants) to the point of being more mean-spirited than funny)
 * Bowser (SMG4 seasons 2014-2015)(he used to be a misunderstood villain of the series who was insecure on the inside. In seasons 4-5, he became a moronic comic-relief who is obsessed with "swag" and "being fabulous" (an easy example of this is in the 2014 episode, "SwagQuest", where he's overly obsessed with making Luigi hip for a swag party at Peach's Castle). Similar to Toad's 2014-2015 flanderization, this is typically played as a cheap attempt at comedy.)
 * Fishy Boopkins (SMG4 mid 2017-present) (he essentially became an anime-obsessed weaboo who in almost, if not every, episode he appears in, he mentions anime or anything related to that)
 * Jimmy (Jimmy Two-Shoes Season 2); became more of an idiot.
 * Duela Dent (The New 52; became an edgy flesh-face wearing sociopath)
 * Heloise (Jimmy Two-Shoes; Became a punching bag)
 * Reginald "Shark" Kastle (Yu-GI-Oh! Zexal) became a stereotypical emo and bland tyrant who is revealed to be a Barian Emperor named Nash, and thinks Yuma and the others are not his friends.
 * Rio Kastle (Yu-GI-Oh! Zexal) became a bland remorseless girl who is revealed to be a Barian Emperor named Marin, and thinks Yuma and the others are not her friends.
 * Aster Phoenix (Yu-GI-Oh! Arc-V) became a ruthless individual who thinks hurting people in dueling is wrong from Leo Akaba.
 * Banjo (Banjo-Kazooie Nuts & Bolts) got flanderized literally into a lazy bear. Sure, the sequels before Nuts & Bolts did show Banjo's lazier side, but Nuts & Bolts did it a lot worse than before to the point that he can't do anything himself thus being an obstruction to Kazooie.
 * Picard (Star Trek: Picard) became a senile anti-male privilege caricature instead of a selfless hero in the TNG.

The Overall Reason Why This Trope Sucks

 * Basically, this trope serves as reverse character development, where the characters you love become more unlikeable.