Nightmare Fuel / City of Heroes

• The "Dark Astoria" zone. Permanently twilit and fog-enshrouded, with the sounds of muted bells and wind in the background, and populated by ghostly pedestrians who are visible only from a distance and vanish if you get too close to them — except for the items they're carrying. (It also doesn't help that Astoria's neighborhoods and landmarks are named for horror movie directors.) Compared to the environment, the walking dead, evil shamans and malevolent spirits inhabiting Dark Astoria are something of a welcome relief.
  • ... Or it would be, if it wasn't known that those evil shamans and malevolent spirits of the Banished Pantheon sacrificed every single man, woman and child in an attempt to awaken Mot, the below mentioned Eldritch Abomination.
  • It's even worse in the Issue 23 expansion, where the Eldritch Abomination that killed everyone in Astoria and created the zone as it was wakes up. Cue some lovingly-detailed Lovecraft tributes and a rare example of a disturbing High-Heel–Face Turn. Not to mention that said Eldritch Abomination will be whispering eerie threats to you as the story arc of Issue 23 rolls onward...
• The Croatoa zone itself isn't that frightening (it's rather beautiful, for a pixellated environment). Some of the instanced missions within the zone are another story. Mainly the ones involving the ghosts, which look like floating, green-glowing, slightly zombified people who as they attack shoot several black, glowing skulls at you. And especially instances with the "spectral chill" fog, that you can't see through, and which lowers your combat capabilities.
• For a real nightmare moment, turn up your sound enough to hear the death sounds for the Croatoa Ghosts. When they snuff it they make bloodcurdling screams of dying agony.
• The First Ward. Originally meant to be a shining example of what life could be under Emperor Cole's rule in Praetoria, before that reality's version of the Hamidon tore into it. But that's not even the worst of it. There's all sorts of paranormal spookiness going on, and the player would end up discovering some creepy things...
  • The Apparitions—they don't have any real distinct form, project blasts of penumbral darkness, and seem positively unhinged when they do speak. But it gets worse: when looking into the memories of a rogue Seer, you find out that these aren't even proper ghosts, but the fractured memories and personality traits that Mother Mayhem lanced from her "patients" to make them more compliant! Sweet dreams...
  • When exploring some of the abandoned Seer facilities, the player would find the Awakened, Seers whose psychic abilities had mutated them in horrific ways—"tumors" that took up most of their heads, sprouting creepy tentacles for good measure!
  • The Awakened, all of them were former Seers that Mother Mayhem experimented on and subsequently discarded for either holding too much psychic power or their psychic power disfigured them. All of them are understandable angry at the fact they were discarded and left to rot in hidden facilities in First Ward. The Awakened lash out via attempting to hi-jack the Seer Network and successfully hi-jack many Seers that were brought along by T.E.S.T. The more powerful Awakened are all mutated by their powers in someway to the point they look almost eldritch.
• One of the alternate universes you could explore when doing missions for Portal Corp is a dead world populated by nothing but ghosts, similar to certain Croatoa missions. And all the ghosts are REALLY angry at you for some reason, calling you a traitor and thinking you were killed ages ago. Eventually you find the diary belong to This Universe!You... who has killed every single person in the ENTIRE UNIVERSE. It seems that this version of you is also dead judging by NPC chatter and the fact that you find this diary in a pile of bones, but... what if s/he isn't? And even if s/he is, there's still the fact that you now know are capable of being the destroyer of YOUR world. Just one bad day away...
• The Dying Praetoria mission for villains and rogues. You are sent into Praetoria by Arachnos after Cole's disastrous defeat to retrieve something and the first thing you see is large skyscraper tall tentacles destroying what used to be Imperial City, Arachnos fighting for their lives against Hamidons hordes of Devouring Earth and Infected Praetorians in the streets and the giant Avatar of Hamidon moving to destroy everything.
• Arachnos is this when you get down to it. A splinter group of Italian fascists in World War 2 Arachnos has become a global threat to both heroes and villains alike after Lord Recluse took the organization over from its founder, The Weaver. Lord Recluse took over the Rogue Isles after assassinating President Marchand and turned it into the nicknamed in-universe City of Villians with Arachnos and some chosen elite villians as his top brass in spreading discord across the Isles and beyond. Arachnos as a organization consists usually of every awful person you can think of. The sociopathic soldiers that enjoy killing, corrupt bureacrats, and power hungry madmen that will soon kill you even if your a fellow member of the organization just to get promoted. The worst part is Recluse, being one of the worst villains out there, actively encourages Arachnos to be as awful as they are reasoning that this is just how humans are so they should embrace it.
  • Some branches of Arachnos are horrifying in their own. From the Fortunata and Bane branches that are psychic soldiers that are part of a psychic network very similar to the Praetorian Seer network. To the violent thugs in the Wolf Spiders that are basically corrupt cops with too much fire power at their disposal, to the eeriness of the magical and eldritch Mu. Arachnos has no shortage of monsters within its various branches.
  • Tarantula Mistresses, just Tarantula Mistresses. Text blurbs in-game confirm that Tarantula Mistresses are psychic humans, usually specifically chosen Fortunata, that are integrated into a spider chasis in a attempt to turn them into even more dangerous psychic soldiers for Arachnos than a usual Fortunata. Analysis of their in-game models makes it very clear that the process for turning someone into a Mistress is horrifying. The only visible human parts of the Tarantula Mistresses is their face at the front of the chassis and maybe their arms and legs that are jammed into a couple of the spider limbs and the abodomen. It's implied that the Fortunata is mutilated via cutting off body parts like limbs to forcibly integrate them into the chassis. Not many Fortunatas survive the integration but the ones that do are exceedingly dangerous, able to even kill the most powerful heroes and villians all on their own.
  • The Fortunata Seer Network and Bane networks are heavily implied to brainwash all of their members into being subservient to Arachnos and will actively scan peoples minds in the Isles for dissent towards Recluse. If you are born as a psychic in the Isles your fate is either to be pulled into Arachnos to be forced into the Fortunatas or to become a villain or hero that may end up being killed or forced in anyways. A alignment mission implies that you can escape the Seer network but that you will be hunted by Arachnos for the rest of your life for it.