Nickelodeon was absolutely essential viewing for youngsters growing up in the '90s. While it’s remembered for kid-friendly sitcoms like Drake and Josh and Zoey 101, the network made its mark on history with a series of irreverent, naughty, and boundary-pushing cartoons. Even if the content was always kept light-hearted and kid friendly, the adults watching with their children could conjure up a giggle or two when jokes went over children's heads.

Many of these shows catered to its audience of middle schoolers with a cast of fresh, young faces. Anthropomorphic characters like Ren & Stimpy and the Australian wallaby Rocko were pretty ambiguous in their age. However, shows like the wish-fulfilling Fairly OddParents, science extravaganza Jimmy Neutron, and even The Rugrats ensured that their naïve protagonists were just as fresh and bright-eyed as the average ten-year-old Nicktoons fan.

With the advent of internet fan art, we’re now living in a world of opportunity. Characters stuck in perpetual infancy have been rendered as adults by talented, and occasionally, twisted artists.

Here are our favorite awesome and creepy examples of 20 Nickelodeon Characters All Grown Up.

20. Dora Everdeen

Dora the Explorer has been a Nickelodeon mainstay ever since the plucky young adventurer’s debut all the way back in 2000. Airing for 14 years, it overtook Blues Clues as the Nickelodeon series with the highest number of episodes. The show followed the adventures of a young girl who travels the world with her speaking backpack and white monkey. She is of hispanic origin, which allows her to teach kids words in the language, in addition to maths and other educational topics.

Sadly, kids today won’t be growing up with the adorable Latina’s teaching skills and brave attitude. There have been a couple of spinoffs, but Dora’s been missing from our screens now for a number of years. There is, however, a live-action film in the works, though you can say that about pretty much everything these days. This doesn't mean there is a lack of excitement for the Dora movie, but it's difficult to say which franchise wouldn't qualify for one.

Thanks to Dora’s adventures, fan artists often draw inspirations from other female heroines when depicting her as a young woman.

This piece, complete with a vicious looking Boots, definitely has shades of Katniss Everdeen from The Hunger Games, complete with a bow and arrow.

19. Reptar Land

We’re well-aware that the Rugrats don’t need fan artists to imagine how Tommy, Chuckie, Phil, and Lil might look when they’ve got a few more year on them. All Grown Up ran for five seasons, after all, and was nearly as popular as the original show. That being said, fans don't necessarily feel as though a spin-off series has done the original justice. Some fans take it upon themselves to create art that depicts what the spin-off may have been missing.

This piece is too irresistible not to include, and it’s safe to assume that it reimagines the squad slightly older still. Lil’s mother certainly wouldn't have let her dye her hair with a red streak when she was eleven years old! Angelica's mother may not have been so keen on her putting makeup on at that age either. Paying a little attention to the picture, you'll also notice they're eating cereal on a roller coaster -- what's going on here?

Featuring the whole gang, it’s a gorgeous send off to the series that many of us grew up with, and even takes care to include a little tribute to Reptar -- the Godzilla clone who was all the rage when the Rugrats were crawling around in diapers.

18. Sandy Cheeks

SpongeBob SquarePants has a cast of iconic characters. There’s, of course, his grumpy employee, Squidward, Krusty Krab boss Mr. Krabs, and his best friend Patrick. SpongeBob artists were kind of asking for more pushy fan art when they revealed that SpongeBob’s other, more mammalian friend, Sandy Cheeks, wears a bikini underneath her diving suit.

Don’t worry, we’re not going to show you a grown up squirrel in a purple swimsuit, as for our purposes, this toned-down representation of Sandy is more like it.

Luckily, Sandy’s sweet astronaut-like diving suit is cool enough to warrant its own sweet fan art. She’s, of course, practicing her karate high kick that we’re sure she’ll try on SpongeBob later on, and has some awesome thigh high cowboy boots in tribute to her Texan heritage. Just don’t make fun of her for that, because as they say, everything's bigger in Texas, and Sandy's wrath must also follow that same logic.

Complete with an acorn belt, Sandy is ready to take on the world, alongside her friends SpongeBob and Patrick. We can't wait to see what kind of hijinks they'll get into.

17. Teenage Mutant Ninja Turtles

It’s hard to comprehend, but the Teenage Mutant Ninja Turtles are still going strong, more than thirty years after their original appearance in the comic books in 1984. They’ve been on our screens since 1987 with no sign of slowing down. They’ve featured in six live-action films and a rebooted series, Rise of the Ninja Turtles, is scheduled for later this year. Although the more recent movies may not have been as successful, their previous cinematic representations have done amazingly, cementing them in pop culture until the end of time.

Of course, such a popular series has generated piles of fan art. Not all of it is savory – just take a cursory glance at any fan art including the turtle’s journalist friend April O’Neil – but some of it is downright awesome.

This piece ranks especially high, which reimagines how the turtles could look in a slightly more realistic live-action adaptation, with each teenaged hero positioned as a different species of turtle. It’s different, but much cooler than Michael Bay’s gross monstrosities. This version also gives them the mean looks they so-well portrayed in the animated series, and that gives every turtle a little something extra.

16. Jimmy Neutron

Sadly, Jimmy Neutron has gone the way of Shrek after a series of bizarre memes hit the internet, but many forget that it was a classic show in its own right. Don’t let the dated animation fool you, the original film was impressive enough to earn itself an Oscar nomination for Best Animated Film, and the subsequent TV spin-off (that’s right, the movie came first), launched CGI animation for television into the mainstream.

Jimmy was the brightest kid inventor on television when his show was still on and there’s no doubt he’d remain an engineering genius as he grows into adulthood.

This artistic rendition swaps his schoolboy attire for some short shorts and a tank top, so he can withstand the scorching heat of being inside the engines of his crazy inventions.

Jimmy Neutron would get into various situations that always left him with few options, but to create a device or devise a plan that would allow him a safe exit from whatever situation he was facing.

We’re glad he’s kept that ridiculous hairstyle, albeit with a little modern flair, as many would still rock the hairstyle today. Thinking back, it's easy to see how this modern haircut resembled the character's previous hairstyle.

15. King of the Ghost Zone

Danny Phantom totally rocked, but sadly, it’s been overshadowed somewhat in comparison to Butch Hartman’s other wildly popular show, Fairly OddParents. It ran for only three seasons, but enjoyed critical acclaim and a dedicated fanbase. It was also way ahead of its time in terms of superhero shows, tackling more adult themes usually reserved for live-action comic book fare. Needless to say, comic book fare is still wildly popular, but this cartoon had quite an interesting spin on the whole genre.

It stars Danny, a teenage boy with ghost-hunting parents who attempt to travel into the Ghost Zone through the use of a scientific portal. When Danny goes exploring in the alternate dimension, the portal fails and fuses his DNA with ectoplasm, transforming him into a half-ghost.

This dark piece of fan art reimagines Danny as the new ruler of the ghostly realm. You might mistake his evil companion as DC’s Poison Ivy, but that’s his best friend, Sam, who has succumbed to the plant ghost, Undergrowth. This fan art pictures Danny as if he came right out of a DC comic, fighting alongside Batman and the like. Who's to say Danny wouldn't have been a part of the DCEU, in some alternate universe?

14. Doug & Roger

Doug is one of Nickelodeon’s original cartoons, and still among their best. Airing alongside Ren & Stimpy and Rugrats in the summer of 1991, it ran for four season on Nickelodeon before being bought by Disney and moved to ABC. The show followed the school life of teenagers, along with their everyday problems and situations. Dealing with parents, friends, and classmates in an open manner, it gave way to some groundbreaking material at the time it was conceived.

It was heavily inspired by the childhood experiences of the show’s creator, Jim Jenkins, as an awkward new kid on the block with an overactive imagination. Taking a cue from The Simpsons, many characters inexplicably have colorful skin tones, such as Roger, Bluffington’s green bully. It seems logical that the bully be colored green, as it served to give him an almost villainous look.

This piece imagines a world in which the series never stopped, and the characters actually aged into their teenage selves, something we wish we could eventually see happen. While they’re a little taller and their cheekbones are a bit more defined, not much has changed. Doug is still a bookish sweater-vest enthusiast, and Roger is the same old greaser with crazy hair.

13. Hey Arnold!

Nickelodeon shows can essentially be split into two categories: the dirtier, innuendo-ridden series that tend to feature anthropomorphic critters, and then you have a host of shows devoted to the experience of being a kid. Whether they’re realistic (Doug) or fantastical (Fairly Odd Parents), Nickelodeon found the perfect niche of whacky, relatable stories for kids unwinding after a hard day at school.

Hey Arnold! was the absolute pinnacle of this. One of the network’s more grounded shows, it followed a group of kids who were practically on the brink of poverty, but still went about their day with a smile. The show dealt with homelessness, abuse, alcoholism, among other adult themes. Even if it was a show for kids, it presented those topics tastefully and allowed children to see a side of life they may be too fortunate to have to deal with. The series definitively ended with 2017’s Hey Arnold! The Jungle Movie, with the characters not having aged a day despite the series’ long hiatus.

We have this piece to thank for imagining how the whole Hillwood gang could look in their 20s.

Every character is easily recognizable, as they all have their iconic features, such as Arnold's hat or Olga's pink shirt.

12. Danny Phantom Anime

Despite Nickelodeon’s impressive array of content, anime still reigns supreme as the world’s most popular animation style. For every American animated show, there’s at least ten anime in syndication, and most are popular enough to warrant an English dub. Although, if you’re really cultured, you’ll stick with the subtitles. The reason this statement rings true is due to the fact that many, if not all anime fans prefer to watch the shows with subtitles, as it adds to the authenticity, as well as allows them a little cultural exploration.

It’s only reasonable, then, that many pieces of fan art take their stylistic cues from the Japanese medium. It’s clean, it’s simple, but it can also be crazy enough to take fan art pieces in strange new directions. We challenge you to find a TV show or movie that doesn’t have accompanying fan art adapting it to the anime style. Honestly, there's no reason that artists shouldn't explore that style.

This anime rendition of Danny Phantom is pretty simple, but updates his superhero costume with a wicked new look and, of course, gives him the patented crazy anime hairstyle. In addition, the green gem on his neck also adds to the anime comparisons, as they often highlight precious stones as sources of power.

11. Dora the Tomb Raider

We were thankful to discover that most of the fan art depicting an aged up version of everyone’s favorite little explorer are actually rather wholesome, simply imagining her as the obvious fearless person she’s destined to become. Compared to many other renditions of fan art, that usually involve quite a bit of unsavory character designs, Dora ones inspire young girls to follow along in her footsteps.

This Hunger Games inspired art already invokes a little bit of Lara Croft. At least, it reminds us a whole lot of Tomb Raider’s penchant for guns, which may not seem like the best idea for a young girl to own, but looks cool anyway. No one would want to cross paths with this one in the forest, as it's unsure whether she'd assist, or plunder your belongings.

This piece goes full on Angelina Jolie with a Lara Croft inspired look that’s straight out of the classic games, and movies made in the early 2000s.

Adapting Dora’s classic look into a tight, cropped jacket, complete with sporty under-armor and a pair of essential cargo shorts, this is an action heroine who’s not going to let Swiper get the best of her this time.

10. Invader Zim

Invader Zim was pretty underrated, but has thankfully enjoyed a revitalized fandom in more recent years. It ran for a pitiful two seasons (just 27 episodes, a woefully low number for an animated kids’ show), but has been dubbed a cult classic thanks to a resurgence of fans. Even at the height of its popularity, the show clearly wasn't able to get the audience it required in order to last longer than the measly 27 episodes it did.

It’s now become so popular, that a new television film has been announced for this year. Let’s hope enough people watch it that we could maybe get a long overdue third season. It would certainly be nice, as the following for this show in the past is comparable to Rick and Morty's following today.

The series followed an invading alien from the planet Irk, Zim, who, along with his useless robot companion, Gir, tries to analyze human weaknesses for an eventual planet takeover. This artwork faithfully recreates the style of the show, and ages Zim up to full on supervillain mode, complete with a set of Doctor Octopus-like robotic tentacles. Although the comparison to Doctor Octopus goes over our heads, Zim looks cool anyway.

9. Ren & Stimpy

Cartoons in the '90s were pretty gross. Take away the raunchiness and hidden adult gags, and Nickelodeon still had a bunch of shows with gross out humor and a generally off-putting animation style. Count the number of booger jokes in your average '90s cartoon on your fingers and you’ll soon be moving on to your toes.

Ren & Stimpy was one such gross out show that was hilarious and innovative. It was so disgusting, though, that the adult show based on these characters that was eventually made, for a more mature audience, wasn’t that much worse than the original kids’ show. It may have been short-lived as an adult show, but one need not stray too far from the original cartoon to get their fair share of disgusting humor.

These pieces are some of the most accurate fan renditions of Ren and Stimpy, in that they’re totally grim. Borrowing the realistic style that older episodes of SpongeBob SquarePants would use for their repellent close ups, the level of detail is amazing but, frankly, hard to look at. SpongeBob wasn't the only one who had these gross close ups, though, as Ren & Stimpy pioneered this, focusing on many of our titular characters' body parts in a very detailed manner.

8. SpongeBob and Patrick

If you thought Ren and Stimpy were gross, some of the artwork for SpongeBob and his friends is strange, but we can’t help but love it. Stepping right out of your nightmares and onto this page, the above absolutely strikes fear into the hearts of children. For one, we're no longer sleeping with the lights off.

SpongeBob was always known for those crazy detailed close-ups that rendered the show’s characters wrinkly, spotty, hairy, and greasy -- bound to make a kid watching Nickelodeon on a Saturday morning cough up their breakfast cereal in disgust. It isn't only that the show aimed at grossing out children, but we wouldn't even want to imagine what that looked like, so one can assume the showrunners to do it for their own pleasure. Who in their right mind would like to know what the elbow of a sea sponge looks like?

This artist seems to have taken that premise and ran with it, but maybe a little too far. A super-realistic recreation of SpongeBob and his best friend, Patrick Star, we’re very glad that Paramount Pictures didn’t use this concept for their 2015 combination of traditional and CGI animation, The SpongeBob Movie: Sponge Out of Water.

7. Jimmy, Carl, and Sheen

We’ve mentioned the boy genius before, but Jimmy Neutron, despite his uber geekiness, managed to find a loyal, if a little socially awkward, group of friends who could tolerate his constant inventing. Jimmy, Carl, and Sheen have been accompanying Neutron through some of his adventures, which made for a little less solitude in the advanced world of inventions he created.

This piece renders the iconic trio as teenagers who are still going on whacky science adventures, no doubt.

It’s a little disappointing that the chunky, bespectacled Carl has been drawn so slim and, let’s face it, good-looking, but we guess it’s a good thing he managed to lose some weight during his teenage years. The other two seem a bit mischievous, with that little smirk on their faces and their general demeanor. Their hairstyles are far more contemporary, though, similar to the previous Jimmy Neutron entry.

What you may not know is that the Jimmy Neutron saga didn’t end with the original series. A few years later, Jimmy’s irritating yet devoted friend Sheen starred in his own spin-off show, appropriately title Planet Sheen. Sadly, most agree that the short-lived series was average at best and couldn't stand up to the genius of the original.

6. Helga

Romeo and Juliet is one among many romances that have transcended the ages to become the stuff of legend, but there are few examples of unrequited love that have captured the imaginations of fan artists than Hey Arnold!’s Arnold and Helga.

Helga’s character traits arise from that age-old cliché that, however mean a girl is to you, the more she must like you. Helga is madly in love with Hillwood’s chillest resident Arnold, but bullies him so not to attract suspicion. Throughout the entire run of the cartoon series, audiences see Helga struggle with her feelings, as teasing Arnold is a satisfying way to get his attention, but is also difficult to deal with. She doesn't want to make Arnold feel bad, but she doesn't have the capacity to handle her feelings differently at the moment.

Not surprisingly, this is one of the cleanest examples of Helga fan art that exists, as any artist pitched with the concept of aging up a teenage romance is always likely to go a little too far. She seems to have wizened up and shaved her iconic bushy uni-brow, but is still looking as mean and boisterous as ever, ready to play another prank on her beau.

5. Rocko's Modern Life

If you haven’t seen Rocko’s Modern Life, you have no idea just how unclean a Nickelodeon show can get. Everyone remembers the wallaby’s short tenure as a phone hotline worker, but practically every episode has at least one surprising joke that is sure to raise the eyebrows of on-looking parents. The series as a whole was a bit controversial, as anyone paying close enough attention can get jokes that are meant only for the wisest, most mature onlookers. Although some others were immature and stupid at best, the general consensus of the show is that some of its aspects went too far.

The show featured a cast of characters including Rocko, a down on his luck wallaby from Australia, as well as his best friend Heffer, the yellow bull, Filburt Shellbach and his next door neighbor Mrs. Bighead, who’s constantly trying to make a connection with Rocko.

This piece ages the trio of friends up, along with Rocko’s dog Spunky, with a little more detail that still embodies the surreal style and dreamy colors of the original series.

4. The Wild Thornberrys

The Wild Thornberrys was absolutely amazing, and not just because it’s generated a whole bunch of memes involving the Thornberry’s father, Nigel. Keeping that in mind, one can imagine that Nickelodeon shows tend to do that a lot, as their inspiration is far beyond what many may expect from children's programming.

The show starred the vocal talents of the amazing Tim Curry as the father of a group of adventurers with their own exploration television show. The Thornberrys would travel the world, looking for new areas to explore and species to discover. The series ran for six seasons, and popular enough to spawn four movies, including a crossover with the Rugrats and a theatrical release which was nominated for the Oscar for Best Animated Feature. It's not enough that the show went on to inspire a movie, but in addition, almost won an Oscar? Impressive.

This entry imagines an older Eliza Thornberry, the Thornberry’s middle child, as well as her teenaged sister, Debbie, and their younger brother, Donnie, who’s a little different, in general. Clearly inspired by Tarzan, though, he’s more of an illiterate George of the Jungle -- Donnie is a feral child the Thornberry’s found and adopted somewhere in the wilderness.

3. Fairly OddParents

After SpongeBob SquarePants, The Fairly OddParents is definitely the blockbuster Nickelodeon show. It’s nowhere near as popular as it used to be, but it was airing new episodes from 2001, all the way until last year, and it still hasn’t been canceled. It’s also generated a live-action television film, starring Drake Bell from Drake and Josh. Although the show may not have the same appeal as SpongeBob does, in terms of content, it still gets the attention of almost as many viewers in it's 17 year run.

If you don’t know the premise, it follows the magical adventures of Timmy Turner who would live the worst life a kid could live, if it weren’t for his wish-granting Fairy Godparents, Cosmo and Wanda. Since it’s been showing on TV, the writers attempted to spice things up a little with the addition of Puff, Cosmo and Wanda’s baby. Nothing spices up a kids' show like a fairy baby.

This artist has featured practically the whole cast of a show a few years older, including Timmy’s group of friends and, love of his life, Trixie Tang.

This art absolutely gives the characters the look we've all been waiting for them to grow into, but we may never actually see them animated in this form, sadly.

2. Angry Beavers Humanized

One of the most popular forms of fan art, especially when it comes to kids’ cartoons, is humanizing. This means that the artist will choose a character depicted as some kind of anthropomorphic animal, and reimagine said character as a human, which gives us either awesome or creepy results. Some of the most popular involve a certain blue hedgehog, but take any zoological group of characters and they’re bound to have attracted the attention of a number of passionate, if strange, fan artists. The Angry Beavers are two of these lucky, or unfortunate characters, depending on how you look at it.

One of Nickelodeon’s shorter running shows, it involved the bickering of two beaver brothers, Dag and Norb.

The show followed their adventures, as they both live together in a cabin in the woods, chewing on trees to build dams during their free time.

Despite airing in the '90s, during which every cartoon character was hideous and armed with an arsenal of filthy innuendoes, the two beaver brothers clean up pretty nicely as a pair of two human brothers. They have the corresponding looks on their face that the beavers usually would, which gives this fan art the additional credibility it deserves.

1. Rocket Power

The wobbly line work, potato-shaped heads and bright, contrasting colors may lead you to believe Rocket Power could be the Rugrats spin-off All Grown Up at first glance, but, for a kid growing up, it was far cooler. Surf has always had its own panache attached to it, as it always gave off the impression of coolness and open-mindedness. Thinking about cool surfer dudes, one would easily be impressed by their image as a youth.

You’d be right to assume that the show came from the same minds and stylistic qualities of the Rugrats, but this show was definitely not for babies. Rocket Power came out during the early 2000s’ obsession with everything gnarly and to-the-max, and featured four aspiring athletes who were crazy for extreme sports. Skateboarding, roller blading, BMXing, even the occasional snowboarding that would make Shaun White proud, the show had it all.

This artists rendition of older versions of Otto Rocket and the gang shows them doing one of the things they do best: catching a sick wave. The original art in the show is far less detailed and probably wouldn't allow for tattoos on their characters, but seeing as the characters have grown, we can't expect their parents to have the final say anymore.

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What Nickelodeon character grown-up design was your favorite? Let us know in the comments!