By now, most of us have accepted that anything popular enough will eventually get either a reboot or a sequel, or both. It may take 15 or 20 years, but eventually a series using the same title and characters as a favorite series from our past will find its way to the airwaves. Admittedly, this can be a good thing -- some reboots take an existing property and update it for modern sensibilities, giving it higher quality animation, and occasionally even better storytelling. Meanwhile sequels can often surpass the original, further fleshing out some of our favorite characters in new adventures. But unfortunately, not every reboot or sequel gets such a happy ending.

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For this list, CBR looks at 15 cartoon spin-offs, reboots, and sequels that ruined the original. This list isn’t in any particular order, mostly because it’s difficult to figure out which series was more terrible or did more damage to their respective franchises. Also, there’s one series on this list that’s live-action, but we’re counting it due to its connection to a franchise that is otherwise almost entirely animated. And while the original is still intact and not technically “ruined”, that knowledge doesn’t make watching any of these newer series less painful.

15 AVENGERS ASSEMBLE

Marvels-Avengers-Assemble

When Disney first launched their attempt at an Avengers toon in 2010 in Avengers: Earth’s Mightiest Heroes, they quickly managed to win fans over and erase any potential skepticism from their recent acquisition of Marvel. The series set-up a world that felt close to the comics, filled with tons of shout-outs, easter eggs, as many Marvel heroes as possible, and numerous adaptations of several classic Avengers tales from various eras.

….and then after the Avengers film in 2012 Disney decided to press the reboot button, starting the team over from scratch just to make things resemble the Marvel Cinematic Universe. Suddenly all the cool storylines that had been built up over two seasons were written off so viewers could get a pared down version of the Avengers, with simpler characterization and a less stylized, more generic animation style.

14 THE CLEVELAND SHOW

the-cleveland-show title sequence

Certainly not the worst series ever, The Cleveland Show still earns its spot (the only true spin-off on the list) for being the series responsible for peeling back the curtain and making Seth McFarlane's structure for creating an animated series as obvious as possible.  You take an over-the-top husband, a wife who has to tolerate her husband's shenanigans, add a teenaged son and daughter, plus two things that talk but probably shouldn't (in this case bears and a child far too worldly for his age), add a ton of cutaway gags, and you've got a McFarlane 'toon.

While American Dad played around with the formula just slightly by adding Stan’s CIA background, with The Cleveland Show being literally a spin-off of Family Guy, more originality was needed…and when it wasn’t provided, it made the original series’ sins more obvious. ’s still fun…but only when you don’t think about it hard.

13 SPIDER-MAN: THE NEW ANIMATED SERIES

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Spider-Man feels like he’s always been on television. From his first series in the late ‘60s, to his terrible live-action series in the '70s, all the way up to his multiple appearances in the '90s and 2000s. But the one everyone always seems to forget is Spider-Man: The New Animated Series, the supposed sequel/spin-off to the first Spidey film, which followed Peter, MJ, and Harry Osborn while they were in college.

Spider-Man: TNAS had a ton of problems, starting with its awful 3D animation and sub-par voice acting, but its tie to the film was the problem. Most of the series was devoted to either new or obscure characters to avoid clashing with any potential characters in future films, leaving the show deprived of Spider-Man's iconic rogues gallery. TNAS lasted 13 episodes and all of a single summer before MTV decided to bring the series to a close.

12 THE PEBBLES AND BAMM-BAMM SHOW

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This one’s a bit of a throwback for fans of old school 'toons. Surprising as it might be to hear, The Flintstones was a groundbreaking cartoon for its era, an animated comedy series that aired in primetime -- its target audience wasn’t merely children -- but the entire family. The show often handled adult issues such as how job losses affected the family, adoption, gambling addiction, and much more.

But by the time they decided to do a sequel in the early '70s, times had changed. Networks had all but given up on the idea of cartoons in primetime slots and relegated them to Saturday mornings. So when The Flintstones got a sequel following Pebbles and Bamm-Bamm as teenagers, the series stopped tackling complex issues, and traded their once subtle, realistic characters for far more wacky, cliché ones in order to appeal to children. Not a surprise, but still highly disappointing.

11 FANTASTIC FOUR: WORLD'S GREATEST HEROES

fantastic four worlds greatest heroes

Fantastic Four actually had a fairly decent record with cartoons for quite some time. The original '60s series felt like the animators had found a way to perfectly animate Jack Kirby and Stan Lee’s creation, while the series from the '90’s series took some of the First Family’s comic adventures and adapted them directly.

No one faults Fantastic Four: World’s Greatest Heroes for taking a few liberties, but the show did get kind of weird, with its needlessly anime aesthetics that leave the team looking like they’re trying a little too hard to be hip. Plus, for a team that has such a massive number of potential foes, it’s kind of odd to have Doctor Doom appear in nearly a third of the series 26-episode run. That’s often enough to make one think Doom was actually in the writer’s room.

10 RUGRATS: ALL GROWN UP!

All Grown Up! image.

The original Rugrats show was a beloved part of most '90s kids’ childhoods, and after Nickelodeon aired what came to be a massively successful 10-year anniversary special called All Growed Up, it seemed like a great idea to create a full-on series following everyone’s favorite children after they’d aged up a bit.

Unfortunately, Rugrats: All Grown Up! showed us why not all series are meant to be revisited. Now pre-teens and teenagers, the former Rugrats often found themselves dealing with much more mundane situations like struggling to “fit in” at school, something fans of the original series could have gotten anywhere. The sense of adventure and exploration of the original had been lost, those special personalities they had as babies vanished in a haze of pre-pubescent insecurities.

9 BEN 10

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The first Ben 10 was an original action cartoon created by the minds at Men of Action and first aired in 2005. It started out with a simple enough premise -- ten year old Ben Tennyson finds alien device that lets him transform into other aliens, but built up over time, and fans got to watch Ben grow into his own as a hero alongside his cousin and grandfather, eventually giving us a massive universe that had three spin-offs before finally shutting down in 2014.

The Ben 10 reboot is basically the same concept, but with much cheaper looking animation that leaves Ben and Gwen looking more like toddlers than ten year olds, far more simplistic plots that feel almost insulting in comparison to what the original and its spin-offs offered, and an increased focus on comedy to match Cartoon Network’s current distaste for “serious” kids action series.

8 THE BATMAN

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The original Batman: The Animated Series is a certified classic to people of all ages -- kids love it because it has Batman, while adults love it for its moody atmosphere and mature storytelling…and Batman. So when WB abandoned the popular “Timmverse” for this reboot of the iconic character, it wasn’t surprising that fans felt frustrated, or even betrayed.

Whatever negative feelings fans had were only amplified when they got to actually watch the show. From one of the weirdest versions of the Joker this side of the Suicide Squad film to a Mister Freeze without all the pathos and loss of the one from Batman: TAS, far too often The Batman just felt like a stripped down, less cool version of the '90s series. It got better by season four with the introduction of Superman and the League, but by then who was still interested?

7 THE REAL ADVENTURES OF JONNY QUEST

JONNY QUEST

Though Jonny Quest of the '60s had some cultural sensitivity issues, the show was still one of the most solid cartoons of its era, featuring beautifully drawn backgrounds that drew fans into a pulpy world of spies and super-science, with the Quest Family and their bodyguard Race Bannon diving exciting tales of derring-do each episode.

So of course, the first thing the revival tried to do was throw out all the cool bits, drawing the series “down to Earth” and dialing back the involvement of Dr. Quest and Race to let the kids take center stage, along with adding QuestWorld, Hanna-Barbera’s fledgling, poorly animated virtual reality world that had little to do with the plot. When their sweeping changes failed, the series reverted as much as possible to the original by the second season, but it was too little, too late.

6 DRAGON BALL GT

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The only anime series to make the list, Dragon Ball GT felt like it had a poor reputation before it even really made it to the States to air on television. Known as the only Dragon Ball series not to have much (if any) input from series creator Akira Toriyama, Dragon Ball GT manages to get under fans’ skin for a number of reasons.

Some of the characterizations for such well-established characters felt bizarre, and between bringing back a bunch of old villains for some of their stories and turning Goku into a child again, it could occasionally feel like a “greatest hits” rather than a legitimate continuation to Dragon Ball Z. And all of that is before we get to the complete mess that was Super Saiyan 4. Well, at least the animation was good.

5 BE COOL, SCOOBY DOO!

Be Cool, Scooby-Doo! image.

No matter what else is said about the art design on most of the other series on this list, in nearly every other case it at least looked like they tried. Be Cool, Scooby Doo! on the other hand looks absolutely hideous. It looks like this was the gang's punishment for being meddling kids and finally stumbling into a house that was actually haunted.

It’s a shame, as Scooby Doo: Mystery Inc. was a legitimately smart reboot of the Scooby-Doo concept, introducing a much greater element of mystery and danger. For the first time ever, a Scooby series not only had a serial plot, but it was one that was actually intriguing and worth following, so for the franchise to go from that to this is highly unfortunate.

4 TMNT: THE NEXT MUTATION

Donatello, Venus de Milo, Michelangelo and Raphael posing for Battle in Ninja Turtles: The Next Mutation

This one’s a bit of a cheat as its not technically a cartoon, but it was billed as both a follow-up to both the films as well as the 1987 cartoon, and for awhile was the only way for kids to see the Turtles on television. Airing on the Fox Kids block in 1997, Ninja Turtles: The Next Mutation saw the Turtles face off against a new antagonist in Dragonlord, and his army of humanoid dragons known as “The Rank”.

From low-budget costumes and dreadful fight choreography to adding new characters like Venus while taking away beloved members of the franchise like April and Casey Jones, Next Mutation committed so many sins that it’s no wonder the series only lasted a year and only got 26 episodes before Fox decided the show’s ratings weren’t strong enough and finally pulled the plug.

3 POWERPUFF GIRLS

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Though the original Powerpuff Girls is regarded as a classic, Cartoon Network’s 2016 reboot seemed as if it was doomed from the very start. Creating it with neither the blessing of series creator Craig McCraken or calling on the voice talents of the original Powerpuff Girls, it was no surprise to fans when this new series wound up being nowhere near as good as the original.

The new series is riddled with issues -- from toning down the amount of action the original was famous for, to needlessly adding in internet memes that make the show feel dated and more like its following trends rather than creating them. And all that’s before you get to the removal of key recurring character Ms. Sara Vellum, or the numerous controversies the series has amassed in only a year, or even the consistently inconsistent animation. This is one Cartoon Cartoon they should have left alone.

2 BEAST MACHINES

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Fans fell in love with Transformers sequel Beast Wars because of its complex characterization balanced with zany humor and the series is generally regarded as one of the most well-received installments in the Transformers franchise. Beast Machines on the other hand continued the same level of characterization, but took itself way too seriously, changing the personalities of many key cast members to fit its storyline and ditching the humor its predecessor had become known for.

But the show’s greatest sin likely lies in its ending, in which Cybertron is turned completely “technorganic”-- ignoring the very thing that made the Transformers unique (intelligent electronic life) in order to make some greater point about environmentalism. Beast Machines ruins Beast Wars by not only throwing away everything that made its predecessor cool, but everything that made Transformers cool as well.

1 TEEN TITANS GO!

Teen Titans Go! had issues straight out of the gate, as Cartoon Network canceled two fairly popular cartoons in Young Justice and Green Lantern: TAS right around the time they announced this was in development. Though obviously Go! had nothing to do with either series being canceled, it still took the brunt of the blame for their absence.

That said, it didn’t exactly help that Go!’s quality was kind of iffy on its own. While the original Teen Titans was a massive favorite amongst 2000s-era kids, Go! took most of the aspects fans loved about it and tossed them aside in favor of cranking up the humor, leaving the new series bereft of any drama or serious action scenes. Its still massively popular with kids, but then you can’t really have the original ruined when you don’t even know there is one.

Did we miss a terrible cartoon follow-up? Let us know in the comments section!