Gabriel "Sylar" Gray - Heroes:
Before Sylar debuted on Heroes, there was a huge buildup. Fans wondered, "Who is this guy, and why is everyone afraid?" He was a demented cannibal with the ability to absorb people's powers. Once he appeared, he quickly became the star of the show. It was like, Peter who? He raised the stakes. We looked forward to seeing him sear a bloody line across his victim's forehead. Once he pointed that finger, you knew someone was in for a hurtin'.

Shane Walsh - The Walking Dead:
Shane wasn't always an unstable killer. In spite of his psychotic break, he usually made a lot of sense. While Rick was at Hershel's knee begging for scraps, Shane was ready to mobilize. Unfortunately, his obsession with Lori and the nature of the zombie apocalypse took its toll. His constant undermining nearly tore the group apart. His behavior forced Rick to lay down the groundwork for the Ricktatorship. So we can thank Shane for inadvertently giving him the push he needed.

Mr. Gold/Rumplestiltskin - Once Upon a Time:
Mr. Gold is a liar and a straight-up manipulator. But he's the only thing that keeps Regina/The Evil Queen from being all powerful. Most of the time he doesn't set out to deliberately harm anyone. People come to him, and he gives them options. If they're willing to make a deal, who is he to say no? Technically, his hands are clean.

Ben Linus - Lost:
Speaking of manipulators, Lost really hit the jackpot with Benjamin Linus. Michael Emerson looks like the guy next door, but he's not to be trusted. He's calm, calculated and always three steps ahead of everyone else. His plans have plans. When it came to Ben, there was never a dull moment.

Russell Edgington - True Blood:
We love Russell Edgington because he has no limits. He doesn't understand or care about strategy and rules. So if he wants to go on national television and rip someone's heart out, he will. He lives in the moment, which makes him unstable but also extremely entertaining to watch.

Klaus - The Vampire Diaries:
Klaus is a dirtbag. There's no way around it. While on the show, he's done some seriously heinous things. But as time's progressed, we've learned more and more about his background. Klaus is a product of his twisted environment. When he's not putting on his bad boy facade, he comes across as fairly likeable.

Constance Langdon - American Horror Story:
Constance Langdon is an old school diva. She has a sharp tongue and makes no apologies for her actions. She'll kill someone and still be home in time to cook dinner. She was easily the standout during the first season of American Horror Story. It's no wonder they brought Jessica Lange back for Asylum. She's deliciously evil.

Cole Turner/Belthazor - Charmed:
Cole brought a new meaning to the phrase, "dark side." He's half-human, half-demon and all confused. By nature, he's an assassin and was sent to kill the Charmed Ones. Unfortunately, he fell in love with one of them causing him to revaluate his mission. He genuinely cared for Phoebe and they eventually married. He was a bad boy turned sort of good.

Amanda - Nikita:
Don't be fooled by her looks. Amanda is the living embodiment of an ice queen. While at Division, her job was to mentally break recruits and mold them into the assassins they were chosen to be. If they didn't cooperate, she had no problem taking a hammer to their fingers. Just ask Birkhoff! What makes her so captivating is her steely demeanor. She does everything with point, blank efficiency. It's almost supernatural.

Dexter Morgan - Dexter:
A serial killer who protects the little guy? That's what Dexter Morgan is. Thanks to his job with the police, he has access to everything he needs to find targets, kill them, and ensure they're never found again. On paper, it sounds despicable. But he's going after people who have unjustly escaped the law. That makes it kind of OK, right?

The Joker - Batman: The Animated Series:
How can you not love Mark Hamill's Joker? He's an icon. The Joker is nearly as famous and revered as Batman himself. Yes, he's sadistic, but he's also hilarious. Over the years, he's delivered priceless one-liners and even a song or two. Our personal favorite? "Jingle bells, Batman smells, Robin laid an egg, the Batmobile lost a wheel, and the Joker got away! Oh Joker, thanks for the childhood memories.

Angel/Angelus - Angel: We love Angel, but every once in a while we'd need a break from his emo, woe is me tune. Whenever Angelus reared his ugly head we were in for a treat. He was fun, careless and gave us insight into the past Angel desperately tried to atone for. Angelus was great in small doses. He was like the equivalent of a fun uncle or aunt, who happens to be a vampire.