Today, there's a major contradiction at the heart of many comic book and pop culture franchises. Characters like Batman and Spider-Man were originally meant to entertain children, but changing times and tastes have pushed them into more adult territory. Amazingly, the inverse of this has also proven to be true, as characters from more adult franchises have appeared in kid-friendly fare. As a result of these duel purposes, a character like the Joker can commit atrocities in one medium, but still be marketed to pre-schoolers and their parents as a particularly mischievous clown. As a result of that odd tension, some of pop culture's most sadistic characters have found their way onto children's cartoons.

RELATED: 15 Overpowered Superheroes The Punisher DESTROYED

Now, CBR is counting down some of the deadliest killers who never should've been in kids cartoons. In this list, we'll be taking some of the most ruthless, sadistic characters from comics and pop culture and looking at how they were treated in kids shows. While this list is hardly comprehensive, we'll be focusing on characters who have generally embraced their violent tendencies, so we'll be leaving more conflicted killers like Wolverine out. We'll also be looking at how many animated appearances these characters racked up before returning to their more mature stomping grounds.

16 THE PUNISHER (SPIDER-MAN: THE ANIMATED SERIES)

Punisher Spider-Man Animated Series

While Netflix's The Punisher has given the gun-toting Marvel vigilante a show of his own, Frank Castle made his full animated debut on Spider-Man: The Animated Series in 1995. In a story loosely based on Castle's debut in 1974's Amazing Spider-Man #129, by Gerry Conway, John Romita Sr. and Ross Andru, Castle tried to capture Spider-Man, believing that he was a criminal. After Spider-Man transformed into the monstrous Man-Spider, the Punisher and Kraven the Hunter teamed up to help Peter Parker regain control.

While the Marvel Universe's Punisher is famous for his realistic armory, high body counts and no-nonsense black costume, he didn't have any of those on the cartoon. Instead, Castle wore a teal jumpsuit with a trench coat and used a variety of non-lethal laser weapons. Since then, the Punisher has made quick appearances on Avengers Assemble and The Super Hero Squad, where he, oddly, hated vegetables.

15 DEATHSTROKE/SLADE (TEEN TITANS)

Deathstroke Slade Teen Titans cartoon

Even though Deathstroke the Terminator has been the Teen Titans' nemesis since the 1980s, he couldn't even use his regular codename on TV. Since cartoons used to be skittish around the word "death," Slade Wilson simply went by his first name, Slade, on 2003's Teen Titans. While Deathstroke is usually portrayed as a mercenary, Slade was a mastermind who orchestrated numerous plots against the Titans over the show's five seasons.

While it's still unclear where Joe Manganiello's Deathstroke might end up in DC's films, Slade holds a strong claim to being the best assassin in the DC Universe. In addition to his scores of successful assassinations, Deathstroke has even taken the Justice League out single-handedly. While he still appeared as Slade on Teen Titans Go!, Deathstroke has appeared on Young Justice and Beware the Batman in roles that hue closer to his comic book origins.

14 DEADPOOL (ULTIMATE SPIDER-MAN)

Deadpool Ultimate Spider-man

Underneath his jokey demeanor, Deadpool is a deeply troubled killer who's murdered droves as a mercenary. Even though Deadpool was R-rated, Marvel's Merc with a Mouth has an immensely marketable appeal that's earned him spots in a few cartoons. Shortly after his first appearance in Rob Liefeld and Fabian Nicieza's New Mutants #98, Wade Wilson made some fleeting cameos in X-Men: The Animated Series in the early 1990s.

Since his adults-only animated series hasn't premiered yet, Deadpool's biggest cartoon moment came during a 2013 episode of Ultimate Spider-Man. In the show, Deadpool was an ex-S.H.I.E.L.D. trainee who briefly teamed up with a young Spider-Man. Thanks to Deadpool's eagerness to "un-alive" people, Spider-Man realized that his conscience kept him from becoming like Deadpool. Outside of TV and film, Deadpool has also appeared in numerous video games, from all-ages fare like Lego Marvel Super-Heroes to his more explicit self-titled 2013 game.

13 BLADE (SPIDER-MAN: THE ANIMATED SERIES)

Blade the Vampire Hunter Spider-Man Animated Series

After he was created by Marv Wolfman and Gene Colan in 1973's Tomb of Dracula #10, Blade the Vampire Hunter mainly appeared in vampire-centric tales for years. After Marvel's supernatural heroes had a short-lived resurgence as the Midnight Sons, Blade jumped into cartoons with a 1995 episode of Spider-Man: The Animated Series. While Blade's cartoon adventures were standard kid-friendly team-ups, the cartoon was the first place to give the traditionally human hunter any kind of vampire powers.

Despite his overall obscurity, Blade became the first Marvel hero to carry a successful film franchise, largely thanks to Wesley Snipes ultra-cool performance in 1998's Blade. Although it carried an R-rating for "strong, pervasive vampire violence and gore," the film followed the cartoon's lead and portrayed him as the Daywalker, a half-vampire without the usual vampire weaknesses. In 1999, the comic book Blade manifested similar powers after a bite from Morbius, the Living Vampire.

12 SHANG TSUNG (MORTAL KOMBAT)

Shang Tsun Mortal Kombat cartoons

With its gratuitous violence, gruesome "Fatalities" and controversial history, almost everything about the Mortal Kombat franchise makes it a less than ideal candidate for a kids cartoon. Despite that, the warriors of Mortal Kombat have fought their way into cartoons on two separate occasions. While any of the Kombatants could fit on this list, the ancient shape-shifting, soul-stealing sorcerer Shang Tsung has a particularly vicious history as the franchise's first evil mastermind.

Shortly before the release of Paul W.S. Anderson's 1995 film, Mortal Kombat, Shang Tsung made his animated debut in the direct-to-video cartoon Mortal Kombat: The Journey Begins. In that short, Tsung gained the ability to read minds in addition to his other supernatural powers. In the short-lived cartoon, Mortal Kombat: Defenders of the Realm, Tsung tried to depose the show's main villain, Shao Kahn, and battled Earth's heroes in bloodless, energy-beam heavy fight scenes.

11 LOBO (SUPERMAN: THE ANIMATED SERIES)

Lobo Superman The Animated Series

Before Lobo made his animated debut in the DC Animated Universe, most of his solo adventures were distinctly not kid-friendly. After his debut in Roger Slifer and Keith Giffen's The Omega Men #8, the intergalactic bounty hunter appeared in some relatively tame team books like L.E.G.I.O.N. But once Alan Grant and Simon Bisley redefined Lobo in the 1990 series Lobo: The Last Czarnian, his adventures were filled with raunchy comedy and ultra-violence that made him a cult favorite character for years.

When Lobo appeared on Superman: The Animated Series in 1996, he kept his trademark biker appearance, numerous powers and rude attitude, but he still had a fairly standard team-up with Superman. Although Lobo was deemed too violent to star in a kids cartoon, he starred in an adult-targeted web series in 2000. Since then, he's appeared again as a mercenary in Justice League, Young Justice and Justice League Action.

10 JOHN CONSTANTINE (JUSTICE LEAGUE ACTION)

Constantine Justice League Action

Even though he hasn't pulled the trigger as much as some of the other characters on this list, DC's supernatural detective John Constantine is one of the cruelest characters in the DC Universe. Since he was created by Alan Moore and Steve Bissette in 1984's Saga of the Swamp Thing #25, Constantine has lied, conned and schemed his way into becoming one of DC's most famous mystical heroes. In the pages of his long-running Vertigo series Hellblazer, Constantine's ruthless manipulation and dangerous habits left his friends and foes dead or suffering an even worse fate.

Despite his sordid past, Constantine made his animated debut in a 2016 episode of the light-hearted series, Justice League Action. While his comic book counterpart has only been a member of the magic-oriented Justice League Dark, the cartoon Constantine was a full member of the main Justice League and was hit by an accent-exaggerating spell.

9 MR. SINISTER (X-MEN: THE ANIMATED SERIES)

Mister Sinister X-Men Animated Series

As Marvel's resident mutant-obsessed mad scientist, the X-Men villain Mr. Sinister has committed a number of atrocities in the pursuit of science. Before he made his official 1987 debut in Chris Claremont and Marc Silvestri's Uncanny X-Men #221, Sinister was responsible for orchestrating one of the deadliest events in X-Men history, the "Mutant Massacre." In that 1986 crossover, Sinister sent the Marauders, a group of unrepentant killers, to exterminate the Morlocks, a sewer-dwelling group of mutants that had been shaped by an unlicensed use of Sinister's genetic research.

After that largely successful campaign resulted in hundreds of mutant deaths, Sinister made his animated debut on X-Men: The Animated Series in 1993. While the Marvel Universe's Sinister got his start by experimenting on his own child's corpse, the cartoon's Sinister was a less intense mad scientist who wanted to push mutants to a new stage in evolution.

8 THE SPECTRE (BATMAN: THE BRAVE AND THE BOLD)

Spectre Batman The Brave and the Bold

As DC's Spirit of Vengeance, the Spectre has been finding cruel, creative new ways to kill evil-doers since he was created by Joe Simon and Bernard Baily in 1940's More Fun Comics #52. While the supernatural force has used a few different human hosts, his most frequent human tethers have been the late Gotham City cops Jim Corrigan and Crispus Allen. With his almost limitless reality-warping abilities, the Spectre joined DC's first super-team, the Justice Society, and still stands as arguably the most powerful hero in the DC Universe.

In 2010, the Spectre made his televised animated debut in "Chill of the Night!," a well-reviewed episode of Batman: The Brave and the Bold where he tested Batman's more vengeful side. In the next episode, he teamed-up with Batman, turned the villain Professor Milo into a piece of cheese and fed him to rats off-screen.

7 CLARENCE BODDIKER (ROBOCOP)

Clarence Boddiker Robocop

Even though he might not be the most recognizable name on this list, Clarence Boddiker is one of the cruelest characters in cinematic history. As a crime boss in Paul Verhoeven's 1987 classic, RoboCop, Boddiker was a sadistic killer with a long rap sheet of heinous crimes, including the torture and murder of future RoboCop, Alex Murphy. Thanks in no small part to Kurtwood Smith's over-the-top performance, Boddiker carried a sadistic charm, even when he threw one of his own men into an oncoming police car.

Although he met a bloody end in that film, Boddiker appeared in 1988's RoboCop: The Animated Series. While Boddiker was still responsible for killing Murphy, the show replaced bullets with lasers and turned the sociopath into a more generic Saturday morning cartoon villain. Although he was in the opening credits, Boddiker didn't appear until the show's last episode, where he led a gang.

6 CARNAGE (SPIDER-MAN: THE ANIMATED SERIES)

Carnage Spider-man Cartoon

While Spider-Man's occasional nemesis Venom might have a claim on eating brains, Carnage, another symbiote, has done far worse. Even before he bonded with the Carnage symbiote, Cletus Kasady was a serial killer who claimed to have killed over two dozen people. After he became Carnage in 1992's Amazing Spider-Man #360, by David Michelinie and Mark Bagley, he lived up to his name and unleashed a maximum amount of carnage around the Marvel Universe by killing and torturing regularly.

Even though Spider-Man: The Animated Series was a children's show, Carnage was still a gleeful psychopath when he joined the show in 1996. Instead of actually killing anyone, this animated Carnage was tasked with absorbing the essence of other characters in order to free the cosmic being Dormammu. After the series ended with Carnage's defeat, the symbiote sociopath went on to play major roles in Spider-Man Unlimited and Ultimate Spider-Man.

5 LADY SHIVA (BEWARE THE BATMAN)

Lady Shiva Beware the Batman 1

As the deadliest martial artist in the DC Universe, Lady Shiva has developed an unparalleled appetite for violence, especially hand-to-combat. After her 1975 debut in Dennis O'Neil and Ric Estrada's Richard Dragon, Kung-Fu Fighter #5, she trained under him to be a crime-fighter. After becoming addicted to fighting, she used her martial arts skill to become a mercenary assassin who killed dozens and even ran Ra's al Ghul's League of Assassins for a time. As she walked the line between friend and foe, Lady Shiva eventually formed relationships with a number of Batman's supporting cast members.

After her Gotham connections had been solidified, Lady Shiva played a big part in the 2013 cartoon, Beware the Batman. As her comic counterpart once was, the cartoon's Shiva commanded the League of Assassins on various missions. Instead of explicitly killing anyone onscreen, this Shiva used the Soultaker Sword to steal her victims' souls.

4 SABRETOOTH (X-MEN: THE ANIMATED SERIES)

Sabretooth X-Men Animated Series

Whether he's been working on behalf of the Brotherhood of Evil Mutants, the Weapon X Program or his own nefarious purposes, Sabretooth has carved a path of savagery throughout the history of the Marvel Universe. Although he's famous for his decades-long grunge against Wolverine, Victor Creed debuted as a mercenary in 1977's Iron Fist #14, by Chris Claremont and John Byrne. After Sabretooth took part in 1986's "Mutant Massacre," his savagery came to the forefront, and Creed became an A-list threat to the X-Men.

As Logan's arch-nemesis, Sabretooth has popped up in most of Wolverine's animated appearances. Creed's animated debut was in the 1992 series premiere of X-Men: The Animated Series. Since he couldn't use his usual vicious methods on a children's show, most of his attacks involved throwing his opponents or bloodless grappling moves. Sabretooth was similarly defanged in later cartoons like X-Men: Evolution and Wolverine and the X-Men.

3 PURPLE MAN (AVENGERS: EARTH'S MIGHTIEST HEROES)

Purple Man Avengers Earth's Mightiest Heroes 1

For decades, Zebediah Killgrave, the Purple Man, was more of a potential threat than an actual one. After he was created by Stan Lee and Joe Orlando in 1964's Daredevil #4, the mind-controlling villain was never really more of a secondary threat. When Brian Michael Bendis and Michael Gaydos got a hold of him in 2001's Alias, that all changed. In the mature-readers stories that introduced Jessica Jones, Killgrave was reinterpreted as an immensely dangerous threat who carelessly took lives, and could feasibly take over the Marvel Universe on a whim.

Before his vicious makeover, the Purple Man made his animated debut in a 1996 episode of X-Men: The Animated Series. While he was a small-time villain there, Killgrave achieved much more in Avengers: Earth's Mightiest Heroes. In a 2012 story, Killgrave mind-controlled the Avengers and used them to take over the world, for a month.

2 PROFESSOR PYG (BEWARE THE BATMAN)

Professor Pyg Beware the Batman

Since he was only created by Grant Morrison and Andy Kubert in 2007's Batman #666, Professor Pyg is still a fairly recent entry in Batman's rogues gallery. After narcotics drove him insane, Lazlo Valentin began to use his surgical and chemical expertise to mutilate his victims with power tools and turn them into zombie-like Dollotrons. His biggest plan involved releasing his identify-destroying drug as a virus across Gotham City.

Along with a few other Morrison-created villains, Pyg made his quick animated debut in a 2010 episode of Batman: The Brave and the Bold. Pyg had a much larger role on Beware the Batman in 2013, where he was a regular antagonist. On that show, Pyg and his partner, Mr. Toad, were transformed into eco-terrorists who attacked those who harmed the environment. In a nod to his gruesome comic counterpart, this Pyg used surgical tools and transformed people into animals.

1 THE JOKER (BATMAN: THE ANIMATED SERIES)

BTAS Joker

More than any other character in comics, the Joker walks the line between a kid-friendly crook and a deeply disturbed killer who pushes the boundaries of what's acceptable in superhero comics. When he was created by Bill Finger, Bob Kane and Jerry Robinson in 1940's Batman #1, the Joker was a psychopathic killer. While the next few decades tamed him, the Clown Prince of Crime returned to his roots in the 1970s and 1980s as he killed Jason Todd, the second Robin and crippled Barbara Gordon.

Despite that dark turn, the Joker has maintained a regular presence in Batman cartoons. Starting in 1992, Mark Hamill's Joker found a perfect middle-ground between joy and madness. Still, even that iconic Joker went too far in 2000's Batman Beyond: Return of the Joker, which had to be edited for violence. Even in cartoons, the Joker's inherent menace shows why he's Batman's deadliest foe.

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