Spider-Man: The Animated Series/Nightmare Fuel


 * The Neogenic Nightmare arc of Spider-Man: The Animated Series seems to have been written with the express purpose of traumatizing children. Highlights include:
 * Dr. Connors visibly mutating into The Lizard.
 * Michael Morbius becoming a genuinely creepy vampire. As if that wasn't bad enough, instead of sucking blood through his fangs like most vampires, he drained plasma through small suckers in his palms instead (oddly enough, this change was one of the many, many mandated by the network to make this show less startling). He later ends up as a giant bat monster.
 * Spider-Man himself mutating into a hideous, vicious, terrifying man-spider. And later on, the Vulture, with his youth-draining tech, sucking the youth out of people, lastly Spider-Man... and also absorbing his mutating DNA, causing him to sporadically turn into the Man-Spider himself, but retaining his full intelligence and power of speech, and then later seemingly permanently being trapped as the Man-Spider for the rest of his life. Sure, he brought it on himself, but still. Fortunately for him, he was cured by an off-screen plot device...
 * There was always something subtly disturbing about the storylines involving Hydro-Man - his sheer relentlessness combined with the fact that anything Peter did to him would only stall him for a few minutes was bad enough, but then he died because Mary-Jane tricked him into spending so long away from water that he evaporated, and Spider-Man just had to say that water is so common that it was possible he'd come back one day, which means a) it's possible that he's still sentient in his evaporated form, b) he might return having learnt from that defeat, rendering him genuinely impossible to get rid of.  Yikes.