Even though this thread has a 90% chance of being derailed, I would like at least 1-2 of you to try and contribute to this list.
Mandy (The Grim Adventures of Billy and Mandy) - I never thought too hard about as a kid, but Mandy is a manipulative, cruel sociopath.
Kreacher (Harry Potter) - Not much to be said here. This dude is crusty and bitter, only made benign by his jaded apathy.
Zim (Invader Zim) - Although this show plays him for laughs, his capacity for cruelty is undeniable. In Big, Bad Rubbery Piggy it's shown just how much Zim enjoys torturing Dib.
Mad Dog (Courage the Cowardly Dog) - Mad Dog domestic abuser from the episode The Mask. Sure, he's violent and dangerous, but his good cop/bad cop behavior is thoroughly chilling.
Him (Powerpuff Girls) - Though the show's target audience is too young for his character to become too satanic, the building blocks are there.
I want to add Ren from Ren and Stimpy and The Brain from Pinky and the Brain, but I haven't seen enough of either show to know if they qualify completely.
If I offer to help you in a post, PM me to get it. I often forget to revisit threads.
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