- Many of the show's villains clearly fall into Eldritch Abomination territory. A hell of a lot more than in any other entry of the franchise.
- The show's sheer amount of Body Horror and And I Must Scream. People get turned into Frankenstein-esque zombies or mummies, or get their eyes, bones or brain sucked out of their body...
- "The Crawler" has Cohila, an ancient insect god, kidnap Janine to turn her into his new insect queen. Janine's transformation is especially scary because of the weird, womb-like mutation egg she's trapped in before breaking free from it, gasping for air, then screaming in terror because the front of her torso from (apparently) neck to groin has turned into chitin. Also, she begins to look like a praying mantis at one point, which she's coping with, but she apparently still has eyelids.
- "Killjoys," the episode where Eduardo gets turned into a grinning vampire clown, pushes the concept of Monster Clown Up to Eleven by presenting demons that take on the appearance of clowns and feed on laughter before sucking the victim's entire body into their mouths, leaving only their clothes behind. Think of Pennywise, but with laughter instead of fear... To make matters worse, these demons are drawn to laughter (even the slightest laugh can attract them), they can turn other people into clown demons like in the case of Eduardo, and they will try to force people to laugh if they aren't doing so already.
- The Pied Piper who leads the ghosts out of the city. It turns out that he is also a Humanoid Abomination ghost that projects the ghost from a mouth in its chest and when he doesn't get his payment he attempts to lead the children out of the city as well, and into the sea. The musical riff that the piper plays is scary too.
- What makes it worse is that, unlike the original story, the Piper got what he originally requested as a reward...so he starts demanding a ridiculously extravagant increase like a statue in his honor and an office. It was never about the money; it was about getting the children all along.
- There exists a version of the outro sequence without the theme song, and only has some ambience while the viewer is presented with several disturbingly-detailed sketches of the series' supernatural beasties while some legitimately creepy "ghost sounds" are played back. Without the amazing theme song to groove to, the "ghost sounds" make the presentation of the ghost artwork extra spooky. Several viewers, including some commenters on YouTube, have admitted to being spooked by this "no-BGM" outro for years. Listen to Track 29 here, it's fittingly titled "The Creeps."
- Or you can watch the actual outro sequence here.
- "Grundelesque," which showcases the return of the Grundel. What can be worse than a monster that embodies an Adult Fear: A child abductor? Perhaps most terrifying is its mantra when trying to get Kylie to come out. By all accounts, the Grundel did this to her for DAYS, giving her no peace. And then he stole away her only friend, Jack, while she fearfully begs him not to listen. Worse off, the Grundel has a special obsession and hatred for Kylie due to resisting his temptations in the past and devotes himself to killing her once he manages to get free. Imagine if the nightmare from your past remembered you and came back to finish you off.
- "Deadliners." It's an episode about a Stephen King lookalike who writes about beings obviously based off the Cenobites that were using him to publish books about them that made them real so they can go out and hunt people to use as their flesh sculpture. As expected from such a potentially terrifying premise, the episode had some of the worst Body Horror you'd ever find in a cartoon aimed at kids. Not only that, the monsters are invincible unless their script is destroyed which they try to prevent by forcing the writer to write down whatever horrible fate they have in store for their victims.
- In "Slimer's Sacrifice," Slimer is brainwashed into damaging Eduardo's life support system, to the latter's clear confusion and horror, while grinning widely and then is released to find his friend choking to death before being told he did it all. And the rest of the team has either been brainwashed into the villain of the episode's loyal minions or fighting for their own lives so there was no one coming to help.
- "In Your Dreams" originally was supposed to be worse for Garrett. His mother was supposed to randomly show up in his dream and torture him with a cattle prod! And what made it into the episode (him being knocked out of his wheelchair and being abused in the middle of a ball game in full view of a referee and an audience, with no signs of any of it stopping and with little to no chance of fighting back) is still pretty terrifying, especially when he starts to sound like he's breaking down right before he wakes up.
Nightmare Fuel / Extreme Ghostbusters
The Nightmare Fuel present in this particular series is even higher than in either the live action films or The Real Ghostbusters. One can only wonder what another outing for the Boogieman would have been like.