Joffrey Baratheon, Game of Thrones
Was it the incest or the upbringing, or was he just born wrong? Fans of the Song of Ice and Fire books have debated this point since the '90s, but no matter the argument, there's one point they can all agree on: In the War of the Five Kings, he's the one you'd least want sitting on the Iron Throne.
Stewie Griffin, Family Guy
Animation lets you get away with a lot. A child who was obsessed with killing his mother and various other criminal schemes would be totally unsettling in real life, but as voiced by Seth MacFarlane, Stewie became Family Guy's most (only?) charming character. Just like with Hannibal Lecter, the British accent helps.
Jason McCann, CSI
Played by a young Canadian actor with little TV experience, McCann was a devil in disguise, nursing a violent grudge against cops underneath a beautiful haircut. His mad bombing spree terrorized the entire Las Vegas Police Department until, in one of YouTube's most popular clips, he was gunned down by police off the side of a highway.
Anthony Fremont, The Twilight Zone
As the Twilight Zone episode "It's a Good Life" repeatedly emphasizes, everybody in the small town of Peakesville is awfully fond of freckle-faced Anthony. Of course, that's because Anthony can read their minds, and if they think anything he doesn't like, he'll send them straight to "the cornfield" – and no one ever comes back. Unusual for The Twilight Zone, there's no twist ending here: The townsfolk are going to be stuck living with Anthony until he grows up. But with his godlike powers, will he ever?
Baby Sinclair, Dinosaurs
'90s kids might be blind to Baby Sinclair's true nature, but ask your parents – he was one bad influence. With his incessant catchphrase "Not the mamma!" Baby mercilessly abused his own father with a variety of household instruments, and the whole thing was played for laughs! Who knows how many Baby Boomer dads regretted signing on for parenthood once their kids started watching Dinosaurs?
Jake O'Hara, Law & Order: SVU
Can juvenile sociopaths be reformed, or should they be locked up for good? That was the question in a memorable 2004 episode of SVU, which seemed skeptical that its cherubic teen killer could ever lead a normal life. And yet, the show played fair; in its final-act twist, the SVU team saw the full weight of how monstrous the alternative was.
Alexander Luthor, Smallville
Alexander, a hybrid clone created with the DNA of Lex Luthor and Superman, provides an interesting case study in the issue of nature vs. nurture. Were his evil acts – manipulation, attempted murder and unethical business strategies – a consequence of Luthor's personality and memories manifesting themselves in him, or were they a product of his strange upbringing in a secret lab? Similarly, when he threw off his dark side and became Superboy, was that merely his Kryptonian half coming to the forefront, or did Clark Kent's mentorship redeem him?
Nancy Oleson, Little House on the Prairie
In the 21st century, someone would have hopefully noticed that troubled orphan Nancy Oleson suffered from severe emotional problems and gotten her some psychological help. Unfortunately for Nancy, she lived in 1870s rural Minnesota, where therapy was even harder to come by than electricity.
Madison St. Clair, The Inside
Future iCarly star Jennette McCurdy was TV procedurals' go-to blonde tween in the mid-2000s, playing victims, witnesses and accomplices on all manner of acronym shows. But on the short-lived FBI drama The Inside, the producers flipped the script, casting McCurdy as a violent killer who used her innocent looks to escape suspicion.
Jerome, La Femme Nikita
Three years before Arrested Development, a young Michael Cera showed up on Canadian spy show La Femme Nikita, playing a child who had been turned into a mind-controlling superweapon. We know what you're thinking – him?
Norman Bates, Bates Motel
The teenage Norman Bates of Bates Motel might not be the cross-dressing, shower-stabbing villain from the Hitchcock film – for one thing, his mother is a living, breathing human played by Vera Farmiga rather than a corpse in the basement – but he's still got the body count of a man twice his age. So far, Norman's murderous impulses have been restricted to his periodic blackouts, but you know it's only a matter of time before he goes full psycho.