It is said that good and evil resides in all of us. Whether that's true or not can be debated.
But in the world of television, the transition from good to evil can be an easy one.
Power, greed, jealousy, and madness makes people do crazy things.
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Sometimes the characters who embrace the darkside have no control over their actions. Other times it's a conscious decision.
While some sought redemption, others had no desire to reverse their evil ways.
Whatever their choice, here are 17 TV Characters who let their evil flag fly.
Who did we miss? Hit the comments and add your choice!
Lee - Gotham
When Lee got infected with Jervis Tetch's virus, she went from Miss Goody-Goody to full out badass bad girl. Burying her former lover alive, and then teaming up with Riddler? It was a refreshing change that didn't last nearly long enough for our tastes.
Slade Wilson - Arrow
Slade never intended to become a bad guy. He trained Oliver in all the skills he needed to eventually become the Green Arrow, but after getting injected by a crazy drug, he became Oliver's mortal enemy. After he and Oliver had a battle in which it seemed like Slade died, the Australian bad boy returned as Deathstroke with a death wish for Oliver but was eventually cured and sent to prison for his crimes.
Walter White - Breaking Bad
Sometimes people do desperate things in desperate times, and Walter White was no exception. After Walter learned he was dying from cancer, he turned to the darkside to make sure his family would be financially secure after his death. The all-around nice guy and great high school teacher entered the drug trade and became ruthless criminal and murderer.
Teresa Mendoza - Queen of the South
Growing up poor in Mexico, Teresa never intended to become head of one of the most powerful drug cartels in the world. Instead of running from the men who killed her lover, she took matters into her own hands and faced her fears. She still has a good heart, even if she's in a bad business.
Fiji - Midnight, Texas
Fiji had been Midnight's resident goody-goody until her desire to break her family's curse so she could be with her true love turned her to the darkside. She had no idea how it would change her, but when she got a taste of the darkness inside, she couldn't resist (isn't that always the way?) Seeing Fiji embrace her evil side was loads of fun, but unfortunately shortlived after she once again found her light.
Elizabeth Keen - The Blacklist
How many times as Agent Keen turned to the darkside? Too many times to list. In fact, after meeting Red, she never really recovered from his influence. This is not to say her evil ways are Red's fault, but once she got a taste of the other side, she couldn't resist not following the rules whenever it would suit her needs.
Sam Winchester - Supernatural
Some may know him as Sam Winchester, others as Evil Sam. He has been in the claws of darkside many times from a drinker of demon blood to a vessel for Lucifer. He seems to have been cured of his evil ways, but who knows what's still lurking deep inside his psyche.
Dean Winchester - Supernatural
Bad boy Dean is a magnet for bad. He became a demon to save his life early on from which he fully recovered, but Dean's worst incarnation of evil was when he was possessed by Michael who wanted to use Dean as a way to take over the world. Dean is back to being the Dean we all know and love, but who knows what other evil forces have him in his sights!
Faith Lehane - Buffy the Vampire Slayer
Faith was a slayer who wanted to be good but let her damaged background mess with her head. She let the darkside in because it was an easy out but she eventually realized that despite her former evil ways, she was meant to walk in the light.
Poison Ivy - Gotham
Ivy wasn't necessarily a good girl by any means, but she had a certain innocence about her. After barely escaping from Fish's Doctor Death, she turned much more evil after she downed some weird power juice. Armed with the knowledge that plants were her friends and creating a hypnotic "perfume" to get her way, Ivy has become one of the most dangerous villains in Gotham.
Arya Stark - Game of Thrones
Maybe Arya didn't go completely dark, but she's definitely teetering on the edge. And who can blame her after all she's been through in her lifetime? There is truth to the statement that Arya is a fighter and a survivor and maybe even made of steel, but she's done some pretty bad things even if she sees herself as a purveyor of justice now.
Theon Greyjoy - Game of Thrones
It's been tough for poor Theon. He can't be blamed for his descent into the the darkside. Ramsey changed him, and not for the better, but he's on the road to recovery after a violent past. After all, he is a Greyjoy. And a Stark.
Bill Compton - True Blood
Once he feasted on Lilith's blood, Bill went from perfect gentleman to evil incarnate known as Billith. He went on a killing spree and started a war, but like many good guys gone bad, he eventually redeemed himself before he no longer walked this earth.
Shane Walsh - The Walking Dead
Once a friend of Rick Grimes, Shane eventually became his enemy. Being around zombies 24/7 would do that to anyone, but Shane had only himself to blame going dark. Selfishness is not a good look when the fate of the team is in your hands.
Piper Chapman - Orange is the New Black
Being in the pen will change even the best of people. It's not that Piper was ever perfect, but she did have good qualities until she didn't anymore. Her descent led her to many confrontations, digressions, and stupid schemes, but you have to do what you have to do in order to survive.
Lex Luthor - Smallville
Sometimes the greatest dreams can turn sour when obsession takes hold. Lex Luthor had big dreams but his curiosity about Clark eventually led to his downfall. Once he let the darkness in, there was no turning back, and Lex was never the same again.
Grant Ward - Agents of S.H.I.E.L.D.
Does the past excuse your present? Grant Ward walked the line between good and evil but only because he had a fierce loyalty to the bad guy who was like a father to him. Still, betraying your friends is a bad thing even if you regret it in the end.