Blukic and Driba from Ben 10: Omniverse have been stated several times by the writers to be part of their favourite characters; they were given appearances in a large part of the episodes, played a role in two season finales, there was one episode focused on them which was stated to be the team's favorite (and another one similar has aired later), and lead designer Derrick Wyatt admitted he wouldn't mind them having their own spin-off show. To many fans, they are just another Plucky Comic Relief duo in a show already full of them, with the additional bonuses of being dumb enough to constantly make idiotic decisions, putting everyone in danger in the process, often ending up as a Diabolus ex Machina, and showing signs of Fantastic Racism against one of the other alien species on the Omnitrix.
Ma Vreedle and the Incurseans also got some accusations of being this. Derrick Wyatt contributed to create both, and both were introduced in Alien Force and Ultimate Alien as minor, mostly comedic villains. Once Wyatt took over, the Incurseans suddenly received an entire arc of their own, making them the first major baddies in the whole franchise to not be Knights of Cerebus, while Ma Vreedle made Vilgax cry. To add insult to injury, Vilgax got Demoted to Extra, with his first episode being a filler in the Incursean story arc.
The reboot version of Kevin Levin is a bit of a mixed bag amongst fans. He was initially liked for his new dynamic and powers with Ben and the gang, but then he tended to overstay his welcome thanks to his merchandise skyrocketing. Now, he’s a pest who shows up constantly, even with stories that would be no different with his absense. It seems that Kevin worked best in small doses. He also becomes the player two character in Ben 10: Power Trip, a licensed open-world video game for the reboot.
The Casagrandes has Sergio, who is an actual pet, the pet parrot of the titular family. Despite the fact that a majority of the show's fanbase hates him for being a tremendous Jerkass who causes conflict in nearly every episode, he gets shoehorned into the series so often that characters like Carlitos and Lalo have become underutilized compared to him. He's also made guest appearances in episodes of The Loud House where Lori attends Fairway University, such as "Don't You Fore-Get About Me" and "Crash Course", adding little, if anything to their plots.
Craig of the Creek has Jessica, Craig's little sister. She is clearly a favorite of the writers, Jessica is more focused than any other supporting character on the show and everyone In-Universe loves or praises her for the most meaningless things she does, as well as being included in various subplots that have nothing to do with her. However, several viewers can't stand her and see her as nothing more than an annoying kid who has no growth other than to complicate the plot of her focus episodes while Kelsey and J.P. are pushed to the side, with Craig Took a Level in Jerkass to make her look better. It also doesn't help that more interesting members of the Williams Family or Kids of the Creek are overshadowed to give Jessica more focus. She even got her own Spinoff series when the main one ended.
Midway through season 2, and especially into season 3, Drawn Together became The Captain Hero Show. Almost every episode focuses on him or features him heavily, to the point that fans of other characters became sick to death of him. By season 3, even many fans of Captain Hero agreed with fans of other characters and felt he was far too overused. The writers admitted that they liked to give him stories, with their justification being that the guy is The Ditz and has no morals or sense of restraint so they could make him do anything at all (an important factor in a show where 95% of the jokes are Cringe Comedy) and it would never be out of character for him.
The Fairly OddParents!: Chloe Carmichael was introduced in season 10 and was meant to be the second lead character alongside Timmy. However, she was unanimously hated amongst the fandom for being a pointless addition to an already bloated cast, with many people demanding that she get completely removed like Sparky. Despite this, throughout the entirety of season 10, Chloe would continue being a major focus of the show, sometimes even overshadowing Timmy himself. The show was already on its last legs even before her introduction, so considering that season 10 was the show’s last season, it’s clear that Chloe’s introduction was the final nail in the coffin.
Before her, however, Timmy's Dad and Mr. Crocker slowly began to take over the show in the later seasons, especially during seasons 9 and 10, which led to fans growing more and more sick of them. They even became the main characters of an episode from season 9 at one point! note Timmy's Dad appears in 37 out of Season 9's 43 episodes and 29 out of Season 10's 37 episodes (63 appearances), and Crocker appeared in 31 Season 9 episodes and 30 Season 10 episodes (61 appearances). It only got worse for Crocker when "Chip Off The Old Crock!" introduced his nephew Kevin Crocker, who is literally just a smaller version of him.
Tribore from Final Space has become this for some. He's supposed to be the wacky Crouching Moron, Hidden Badass character but some find him too annoying (his lisp in particular) and unfunny who appears too often. This was taken a step further in season 2 where he joins the main cast, making the already large team of characters even bigger. The fact that he keeps coming back and has almost nothing bad ever happen to him has made people see him like this.
Cubert from Futurama turned into a parody. He was actually created to be one of these, apparently in direct reference to the former Trope Namer, (that being Wesley) and he was originally intended to be a sort of Ace character, except he would still be hated and mistreated by the other characters. Only the last part became true. In his debut episode, the rest of the cast takes an instant dislike to him and manage to get in a few good insults. It helps that the writers were more in tune than others in their profession. Originally, Cubert was supposed to be the character who lampshaded all the ludicrous aspects of the series, which he does in his debut episode. However, the writers realized how annoying this was and transformed him into a standard Bratty Half-PintTV Genius, only using him in a couple of episodes thereafter. He is also downgraded from a genius to an insufferable brat who thinks he's smarter than he is, while still acting like an actual twelve-year-old.
Gravedale High: Frankentyke got the majority of episode focus and screen time in an effort to make him the next Bart Simpson, but he isn't very popular with the fans.
Kaeloo: Despite her status among the fandom as The Scrappy since her introduction, Pretty has continued to receive more screen time than any other secondary character. During her time as an Alpha Bitch she would often be a Karma Houdini, and after her Heel–Face Turn she became universally adored by the other characters in-universe and good at everything she does, leading the other characters to constantly praise her all the time.
Kamp Koral: Nobby and Narlene, but especially the latter, are two trickster narwhals who live in the woods behind camp. They're disliked for how often show up out of nowhere to mess stuff up, and often get away with it entirely. Most of their actions go beyond innocent fun and lean into creepy or flat-out disgusting (shoving a sea urchin into SpongeBob's pants, pretending to flash her breasts at a group of children, selling an addictive G-Rated Drug to kids). A lot of her scenes are also heavy in foot close-ups and gross-out, with the widely-hated "The Taste of Defeat" dedicating an entire sequence to Narlene putting her foot in soup, shaving toenails into it, and then serving it to kids. Narlene also tends to hijack episodes that otherwise have nothing to do with her, such as "Hats Off to Space" and "Regi-Hilled". She also gets two spotlight episodes on the main series, too. And yes, other characters do regularly talk about how great Narlene and Nobby are.
Kevin Spencer: The crew (most likely Greg Lawrence) seemed to love Percy, given how, beginning somewhere around season four, he largely took the main focus of any given episode, including Percy getting to meet Old Barfy ("Ad Beer Add"), Percy meeting his illegitimate son ("Legitimate Claims"), Percy buying a time machine ("That Guy Who Liked Pie"), Percy getting his dick shredded off by a paper shredded ("Blow Job"), Percy running for president ("The Buck Stops Here"), etc., while Kevin (the show's namesake) Anastasia (his wife) and most, if not all of, the supporting cast were either Demoted to Extra or only existed to serve as plot devices. Notably, the intro for the last season is centered around Percy being a alcoholic loser, while Kevin and Anastasia are only given a mention via a single passing lyric.
Alas, his wife is just a big, fat whore / And his son is rotten to the core...
Flip from The Loud House. Despite the fact that many fans hate him for his disgusting and annoying habits and his personality in general, he's gets a lot of screentime and episodes focusing on him to the point where some fans have jokingly decided to call The Loud House "The Flip Show".
There were (and still are) so many restrictions imposed on Disney writers when dealing with Mickey Mouse due to him being the studio icon that any other character in any given Mickey cartoon, as a side effect, got carte blanche to steal the spotlight. Hence how characters such as Donald Duck came to grow in popularity. The strange irony is that this happened because Mickey was the Creator's Pet of Mr. Disney, not the other characters.
The concept of the Creator's Pet was parodied in Robot Chicken. It was done in a sketch featuring the producers of Star Trek: The Next Generation discussing how to make the fans love Wesley Crusher, after the fandom has paid for a billboard threatening to ass rape Wil Wheaton to death. So they decide to include a character so annoying, it would make Wesley look better by comparison. When one writer suggests they try to make Wesley a better character, he gets thrown out of the room. The resulting episode has an annoying Great Gazoo rip-off called "Snirkles", who proceeds to bother Wesley by playing a "space banjo song" and then disappearing. The fans then change the billboard to say "Kill Wesley. Keep Snirkles." Wil Wheaton, after seeing the sketch, tweeted that he would've loved to voice Wesley if they asked him to.
Rocko's Modern Life has an In-Universe example. While working on the "Wacky Delly" cartoon for Rachel (formerly Ralph) Bighead, Filbert becomes very protective of The Cheese, the character he created/voiced.
Cheese: I am The Cheese! I am the best character on the show! I am better than both The Salami and The Bologna combined!
Smiling Friends parodies this trope hard. The episode "Shrimp's Odyssey" starts by introducing the fifth Smiling Friend, Smormu, and urging Audience Participation to see if he stays or not. The poll is stacked in favor of Smormu staying, since the answer for wanting him is just "SMORMU" while the answer denying him was the much longer "NO I REALLY REALLY REALLY DON'T WANT SMORMU", meaning more people are likely to vote for than against Smormu. The results were just barely in favor of Smormu staying as a result. They also had an Electoral College involved, which voted against Smormu, but was overridden by the supposed Popular Vote. At the end of the episode, he arrives to cheer Pip up with a dance, much to his confusion and Charlie's annoyance, and then gets brutally killed offscreen after the credits.
South Park: As the series progressed, Randy became more and more of a Manchild and a Spotlight-Stealing Squad; the fanbase was split about this at first, but as time went on his number of supporters dwindled. Season 23 was where it got particularly bad. By this point, he had moved the family out to the Tegridy Farms marijuana plantation, and for the first half of the season, "Randy tries to sell weed" was an A- or B-plot in every single episode. The best that one can say is that he usually didn't get any Character Shilling, as his family in particular openly hate him... but even then, episodes like "Christmas Snow" focus on how much people love his weed and demand more plotlines around it, to the frustrated screams of the viewers. While early Randy-centric plots showed that he cared about his family (often he got involved in the story because Stan was in trouble), at some point he stopped caring about anyone but himself. Unlike Cartman, who can be a cleverVillain Protagonist and pays for his actions about half of the time, Randy usually succeeds with no consequences because other characters just pick up the Idiot Ball.
Star vs. the Forces of Evil has Princess Pony Head, Star's spoiled, Valley Girl best friend, who outright tries to kill Marco in her first appearance. What's odd is that she does start to slowly grow into a nicer character over the first few seasons, only for her Character Development to suddenly snap back, leaving a self-centered diva who never learns a lesson. To the show's credit, around this point even Star starts to voice annoyance with her flaws, and we learn that the rest of her family consider her the Black Sheep.
Thomas & Friends: Philip had several episodes to himself, especially compared to other new characters, who often faded into the background after a few episodes.
Owen in the first two seasons. The writers and voice actors of the show often wrote glowingly of him (Christian Potenza is quoted as having a man-crush on him), yet he is considered a Base-Breaking Character due to his constant Toilet Humor, Character Shilling (such as Gwen calling him sane even when he does exceedingly odd or stupid things, and the rest of the cast talking about how awesome he was during his elimination in the 2nd season, despite the fact that he cost the team the challenge and spent the entire episode trying to eat two of his teammates), and Character Focus (such as extended dream sequences of him naked and frolicking on mountains made of cheese). His face was even used as the icon for the first season on at least Cartoon Network. However, this decreased as the series went on, the second season giving him a lesser role and the third season giving Owen much less praise from the other contestants, and he received some decent character development with his friendship with Noah and his breakup with Izzy. The writers must have noticed the backlash, as Owen does not appear in seasons 4 and 5, save for minor cameos.
Mike and Zoey, especially once All-Stars aired. Both characters get way more screen time than the rest of the cast on both seasons, even overshadowing the likes of Duncan, Gwen and Courtney on the latter, just to show off their relationship, without having much character development overall.
