Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Nightmare Fuel: Johnny the Homicidal Maniac
In issue three, Squee ends up being separated from his parents (who couldn't care less) at the mall. A man shows up and offers to help Squee find his mom. It turns out that the man is a pedophile intending to molest Squee. Johnny shows up to save Squee by striking the pedophile in the side of the face with a metal pipe. It all goes downhill from there. Johnny then proceeds to use some sort of claw things to tear open the man's head while he's still alive, showing his brain in full view, then rips it out and throws it against the building. Naturally, this more-or-less traumatizes Squee.
Pretty much EVERY PAGE OF THE WHOLE DIRECTOR'S CUT has something that is mortifyingly terrifying. The way Johnny kills people, the way he tortures them, and even the way he attempts to love (he goes on a date with a girl named Devi that he met at the bookstore and then tries to immortalize the moment by killing her) is downright scary. There was one page that showed people in torture devices that not even Jigsaw would have used.
To be fair, Johnny was being (kinda) manipulated by his two dolls, Psychodoughboy and Mr. Fuck. Mr. Fuck tells Johnny, "Freeze it! Forever in time with never the memory of losing it to another day!!" and right after that Devi walks in to see Johnny holding out two knives. If anything, those two voices are quite terrifying because they can manipulate Johnny so easily to do what they want. And Johnny didn't kill Devi. She really kicked his ass. And let's not even get started on the Moose...Also, to clarify on the above post, the tortures involved: being hanged by three hooks; One in an eyelid, another in his other eye, and the last in his crotch, nails in the ears, a nail through the tongue while pulling the head back, forcing an open jar filled with biting insects into the mouth, tearing off a man's arms while sticking them on a sharp stick and spearing them through his brain, stretching the cheeks and pinning them to the ground with knives, once again putting nails in someone's ears and also hanging him onto the wall by nailing his eyes to the wall while they're out of the sockets and attached to his head, electrocution while on a wet table, a man being stripped naked with his feet shackled to the floor while a cobra is within a foot of his crotch, and being completely nailed to the floor. The last panel ends with Johnny writing in his 'Die-ary', "Dear Di-ary, today some friends came over".
And all that's neglecting to mention what's REALLY terrifying about Mr. Fuck and Psychodoughboy; each of them were once an aspect of Nny's personality (Mr. Fuck was his manic side, the part of him that made him want to kill and torture people, and Psychodoughboy was the depressive side of him, the part of his that craved suicide and oblivion) that, due to the influence of the Moose......separated from him. These two...things literally became separate entities, each of them trying to lead him on for their own nefarious purposes (Mr. Fuck driving him to perform more and more carnage, while Psychodoughboy tried to make him kill himself), all while feeding off his mind and personality.
Did we mention that this is contagious? Apparently if Nny cares about you, you might end up like Devi, the aforementioned ex-girlfriend who (on top of everything else) got her own little brain parasite to fight off (which spawned from her own painting). Once discovered, it constantly taunts her as it tries to take over her mind, so that she's fully aware of what happens if she fails: end up like Nny, who apparently tried to fight and lost. Then there's the little boy who can only list his teddy bear as a real friend... and the teddy bear's likely another one of these things!
The implication in I Feel Sick that Johnny could have been a normal person before he became a wastelock is both extremely depressing and terrifying. We don't get much of anything on his backstory; it's possible he used to be mentally healthy and simply fell apart under the influence of the Moose... or he used to have schizophrenia (judging from the manic/depressive Mr. Fuck and Psychodoughboy), which was taken advantage of by the wastelock system and lead to the creation of the various entities that live in his house. Sickness's line ("Your friend thought he could fight...too. And he ended up...introducing us...to you.") could also be interpreted as wastelock-Johnny trying to fight against them, only to fail and degenerate even farther. Basically the whole wastelock system, what it means for people, and how it's spread is one long train ride of pure Fridge Horror.