Kids cartoons have always had elements that people of all ages can enjoy, be it relatable characters, adult jokes or maybe the stories are just appealing to adults and children alike. There are simply some cartoons that don't talk down to the kids watching it, exploring somewhat mature themes in a responsible way. However, sometimes things can get a little out of hand. Sometimes shows get a little too mature, resulting in some crazy dark episodes. We're not talking about some horror movie parody either, there's some seriously f***ed up s*** in kids cartoons. Seriously, nightmare-inducing stuff.

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Who knows where these ideas come from. Maybe it's the crazy imagination of the creators or maybe appealing to adults goes horribly wrong. Either way, it's absolutely insane what managed to get on child-rated television. Dirty jokes are one thing, insane screwed up nightmare sequences are something else entirely. So what are some of the most messed-up episodes in cartoon history? Well, there were a lot to choose from (seriously, a lot), but we think we've got a good list here. Prepare yourself for some nightmares, because here are CBR's picks for the 15 darkest kids cartoon episodes of all time.

15 THE DAY THE ED STOOD STILL

Ed, Edd n Eddy was created by Danny Antonucci, an adult cartoonist whose work was so vulgar he was dared by a friend to do a kid's cartoon series. Though Ed, Edd n Eddy is indeed a kid's cartoon, it's rife with adult humor and themes. It also got pretty dark at times, both in the family lives of the neighborhood kids and in how some of the nutty plots unfolded.

One of the most intense and dark episodes was "The Day The Ed Stood Still," in which Ed decides he wants to be a monster. Double D and Eddy create a costume for him and something snaps in Ed once he puts it on. Ed takes his new role as a monster WAY too seriously, hunting down and attacking the other kids and trapping him in his cereal-crusted nest. Guess Ed is just a psychopath then, that's cool.

14 TO HECK AND BACK

Remember that episode of Rocko's Modern Life where Heffer went to hell? Yes, you read that right, a cartoon cow on a kids show went to hell. After choking on a chicken bone, Rocko's best friend dies, his soul floating off to heaven before his wings are replaced by anvils and he falls straight to "heck."

After arriving in heck — Heffer questions why it's not called hell, only to be censored — a demon named peaches (with udders on his head) tells Heffer that he has committed the deadly sin of gluttony. Peaches shows Heffer all the ways his gluttony has affected those around him, to which Heffer is mortified. Luckily, Rocko resurrects his friend — with a light switch on his heart nonetheless — and Heffer escapes from heck. However, he doesn't seem to have learned his lesson since he asks Rocko to stop for more food immediately afterwards.

13 SPEED DEMON

The Powerpuff Girls DC Comics

Powerpuff Girls had a lot of fun with superhero tropes and cliches, including the classic "alternate future" narrative. In the episode "Speed Demon," the girls race home from school, excited to go on vacation. The race gets a bit out of hand when they start moving faster than the speed of light, causing reality to warp around them. This results in the girls getting flung into the future, but more specifically a future where they disappeared in the past.

Because the Powerpuff Girls weren't around to save the day, the city of Townsville fell prey to crime. This future is a post-apocalyptic wasteland where the city is destroyed and Him has taken over the world. To top off this nightmare world is the fact that every citizen of Townsville has gone crazy, driven insane by anger of the girls abandoning them. That's some dark stuff, man.

12 ONE BEER

Tiny Toon Adventures followed the adventures of the next generation of cartoons as they attended Acme Looniversity. Similar to Animaniacs, the show as divided up into different segments. One of these segments, from the episode "Elephant Issues," was called "One Beer." That title is bad enough, but the plot is even worse.

Buster Bunny asks what his friends, Hamton and Plucky, want to drink, opening the fridge to find an unopened bottle of beer. They decide to drink it, each of them getting drunk from a single sip. After turning away their friends with their drunken state, the three of them decide to steal a cop car. They take the cop car for a joyride before crashing into a ravine and dying, their souls floating up to heaven. The segment was meant to be a PSA, but only served to get the entire episode banned.

11 OVER THE EDGE

Batgirl death in the animated series

That title is rather appropriate since this episode of The New Batman Adventures did just that. We start with the batcave being raided by the GCPD, the entire squad aware that Batman is Bruce Wayne. It appears that Commissioner Gordon has a personal vendetta against Batman, and we learn why in a flashback that reveals the death of his daughter. Batgirl fell off a building while fighting scarecrow, dying in her father's arms as he realizes Batgirl and Barbara Gordon are one and the same.

Blaming Batman for his daughter's death, Gordon uses the entire GCPD to hunt down the vigilante. We get that Batman is the dark knight, but this is just crazy. Luckily, as expected (since they wouldn't kill Batgirl off) we find this entire sequence to be nothing more than Barbara Gordon's nightmare. Still, this episode definitely went over the edge.

10 NASTY PATTY

When you accidentally kill someone, you don't want to go to jail right? So, the logical course of action is to bury the body and hide all the evidence, right? We're joking of course, but these actions are the plot for a lot of dark, R-Rated movies and TV shows. So, why was it in an episode of Spongebob Squarepants? Specifically, Mr. Krabs and Spongebob think they've killed the health inspector after feeding him a "nasty patty," given to him because they think he's a scam artist.

What ensues is a super dark sequence of events in which Mr. Krabs and Spongebob try to stow the body somewhere, only to be "caught" by the police. Luckily, it turns out that the health inspector was just unconscious, but Mr. Krabs and Spongebob have clearly gone down a dark path from which they cannot return.

9 HAUNTED

Though Slade was defeated once and for all by this point in the Teen Titans continuity, Robin begs to differ in the episode "Haunted." Robin, ever vigilant even after the death of Slade, is inspecting an old mask of his nemesis, only to get dust in his lungs. Following this, Robin starts to see Slade lurking in the shadows during a fight with Cinderblock. Robin chases after Slade, but to no avail.

As the episode goes on, we find that Robin has gone slightly mad, seeing Slade while the other Titans cannot. He is beaten, bruised and haunted by these vision of Slade, losing his normally cool composure as he chases ghosts. While we eventually learn that Slade's old mask released a hallucinogen into Robin's system, "Haunted" is still severely dark, exploring themes of PTSD and being driven mad by obsession. That's seriously a lot for a teenager to handle.

8 PIGEON MAN

Arnold watching as Pigeon Man leaves in Hey Arnold!.

Hey Arnold! was known for telling mature stories in ways that kids could understand, teaching valuable lessons along the way. However, it sometimes went a bit too far, like the episode "Pigeon Man."After Arnold's pet pigeon, Chester, gets sick, he takes him to the legendary Pigeon Man, who is nothing like what the rumors say. Pigeon Man heals Chester and he and Arnold form a friendship.

While the two bond, the other neighborhood kids trash Pigeon Man's roof-top home. Discovering the scene, Pigeon Man is once again disappointed in humanity, his pigeons gather around him and fly him off into the sunset. There was a rumor that the episode's original draft had Pigeon Man commit suicide, but it was debunked by the show's creator. Still, the image of a man being lifted by wings into the sunset still paints a pretty dark metaphor of death and ascension.

7 RETURN OF THE JOKER

The Joker himself is already a dark, scary and psychotic villain whose actions and sadistic personality are enough to give anyone nightmares, but Batman Beyond: Return of the Joker takes it even farther. It starts with -- surprise -- the return of The Joker as he forces his goonies to commit crimes and draw attention, leading Terry to investigate. As the mystery unfolds, we learn exactly how the Joker has returned, and how he disappeared in the first place.

Back when Bruce was still Batman, The Joker kidnapped Tim Drake, the second Robin (in the DCAU) and tortured him for information. Tim broke down, revealing Bruce's secret identity, after which the Joker experimented on Robin, turning Tim into a smaller version of himself. Tim loses himself and kills the Joker as a result. Luckily, this dark story made for a great TV tie-in film instead of just being depressing.

6 WEIRDMAGEDDEON

Most of Gravity Falls' nightmarish elements served as a means to make for a kid-friendly, comedic tribute to oddball shows like Twin Peaks. However, there were a few instances in which the show got just a little too dark. We are of course talking about the show's three-part finale, "Weirdmageddeon."

The Weirdmageddeon is a strangely horrific and horrifically strange apocalyptic event that is hinted at and prophesied throughout the entirety of Gravity Falls. When Bill Cipher finally gains enough power, he unleashes this oddpocalypse on the Oregon town, prompting Dipper and Mable to fight back. There's a lot of dark and messed up stuff in these three episodes, but perhaps the darkest moment is when Bill utters the phrase "I've got some children I need to turn into corpses" when referring to the Pine twins. This show had Disney's name on it, folks.

5 THE PUPPETMASTER

Bloodbending in Avatar: The Last Airbender.

Bloodbending is one of the darkest elements (pardon the pun) of the Avatar: The Last Airbender world. It's exactly what it sounds like, using waterbending to control the blood of others and move them around like puppets. The concept alone is already sinister and severely messed up, but the episode in which it's introduced, titled "The Puppetmaster," is super dark.

While hiding out in the Fire Nation, Aang and company are taken in by Hama, a waterbender who escaped Fire Nation prison and has been hiding in plain sight since. Eager to learn from another waterbender, Katara bonds with Hama, learning her painful past as a prisoner of war. Hama escaped her incarceration by developing bloodbending, a sinister and dark technique which Hama shows no reservations towards using. The whole episode is disturbing, especially the sound effects of bloodbending.

4 FOR THE MAN WHO HAS EVERYTHING

Based on the Alan Moore and Dave Gibbons Superman story of the same name, "For the Man Who Has Everything" is an episode of Justice League Unlimited in which Batman and Wonder Woman visit Superman for his birthday. Upon entering his fortress, they find an alien parasite attached to Superman. The alien has Clark trapped in a fantasy world of his own creation, one that he cannot escape.

In this fantasy world, Krypton is still intact and life is thriving on Superman's home planet. He has a wife and child and his parents are alive and well. Kal-El is happy, he has everything he could ever want, but the fantasy is falling apart. Superman eventually realizes it's all a dream and has to say goodbye to the son he loves, dismissing his flesh and blood as mere fantasy. Shut up, we're not crying, you're crying.

3 LONG LIVE THE QUEEN

You know, when you hear that Black Flag frontman, Henry Rollins, is cast as a villain, you better be prepared for one intense character. Yet, nothing could prepare us for the likes of Zaheer. Zaheer served as the villain for season 3 of Legend of Korra, and boy does he live up the anarchist nature of his voice actor. The pinnacle of this comes in the episode "Long Live the Queen."

Fed up with the monarchy of the Earth Kingdom, Zaheer makes his way into Ba Sing Se, planning to take down the Queen. The escaped criminal has recently acquired airbending as part of a new awakening of air nomads. Using his newfound abilities to enact his philosophies, Zaheer takes the Queen's life by bending the air out of her lungs. That's f***ed up, and this show had a TV Y7 rating!

2 FAILSAFE

In the Young Justice episode "Failsafe, "The Team" is subjected to a telepathic simulation to test how well they did in a situation where things got worse and worse. It's merely an exercise to train them to better handle stress, but in the process, things get really dark, really fast.

First of all, the simulation (which we think is real until the end) starts with every member of the Justice League being killed by aliens. Following this, The Team must help defend the world as the last heroes left. However, one by one, each member is killed by the aliens, starting with Artemis. As each member dies, things get worse and worse until Miss Martian is shocked out of the simulation, her psychic mind having taken over the whole thing and making it seem real. All of this was under Batman's order too. Nice job giving teenagers PTSD, Bruce.

1 DARK HARVEST

Dark Harvest episode from Invader Zim

So... Yeah... There was a show on Nickelodeon that had an episode in which an alien began hunting down children so he could steal their organs... What the f***, man. It's baffling how this episode of Invader Zim even aired. Seriously, we'd like to tell you this insanely dark concept is executed in a humorous and cheeky way, but it's not. It's plays like a monster slasher movie.

After Dib points out to Zim that he probably doesn't even have human organs, Zim panics and seeks to gain human organs to appear more human. He takes things WAY too far and begins harvesting the organs of his schoolmates and replacing them with common objects. Oh did we forget to mention the part where he replaces vital organs with stuff? Cause he did! If this didn't give you nightmares, then you're far braver than us.

Can you remember any other kid TV episodes that are dark af? Let us know in the comments!