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Nightmare Fuel: Orphan Black
Helena. She is very disturbing.
The rebar scene. God, that looked painful. The web of scars on her back don't help.
And when she's pulling it out with her blood and guts spilling everywhere in the opening to episode four. Even more terrifying when you remember that a little boy was present and she covered him in her blood. He later called her "The Angry Angel".
She also cut off Olivier's tail.. and danced with it. Yes, he's a bad guy, but still.
Beth's suicide by train is very graphic, and we get to see the effects on her in detail.
A lot of the "enhancements" made by the neolutionists are highly disturbing, most notably Olivier's tail.
By the way, human cloning has progressed much, much further than you think it has. You could be a clone and not know it. There may be ten different people genetically identical to you walking around right now, and you're all being monitored by a shadowy organization of scientists who break into your house at night and conduct tests on you with the connivance of the people you love and trust. Sleep well!
Sarah's non-nightmare about Dr. Leekie's people performing tests on her are extremely unsettling.
Aynesley's death (getting strangled by having her scarf stuck in a sink grinder). To make matters worse, she wasn't even Alison's real monitor!
Amelia's gruesome demise. She shows up at Beth's house and Helena stabs her. Sarah then arrives home to find a huge blood stain on the carpet. She goes down to a warehouse and there's Amelia, beat up and tied to a post with chunks of her torso missing and bleeding from her mouth and abdomen. She went out suffering.
Helena and Sarah's confrontation. Helena shows up with a torch, which gives her a demonic glow, then proceeds to beat the ever loving crap out of Sarah, nearly strangling her with a hugh chain. Sarah grabs a gun and shoots her dead.