Being arguably a Dark Fic...yeah, these happen a lot. Spoilers are unmarked.
- Kaneki developing his kakuja is a mix of this and Body Horror.
- Hell, just Kaneki in general. A bulletproof, Healing Factor-equipped cannibal with Combat Tentacles and a preference for terrifying his opponents.
- Lauren's hallucinogen grenades.
- The Necromonger Pirates are a massive pile of it, thanks to their captain taking Reforged into a Minion and Medical Horror into an art form.
- Almost everything about C. The ghoul is a Psychopathic Manchild par excellence, seeing everything not part of his crew as potential prey, and apparently has a preference for eating his opponents while they're still alive.
- Grigori Venator's diary - which catalogues his slow descent into madness as his attempt at creating a Super-Soldier for the World Government, which resulted in the creation of ghouls.
- Subsequently, The Reveal that the World Government not only was responsible for ghouls being created, but also tried to wipe the species out, root and stem - and failed.
- Ivankinraion Island was inspired by the Metro series, then given a dash of Cthulhu Mythos as well. Most of the Maybe Magic, Maybe Mundane stuff leaves the Nightmares alone, but when it's all woken up at once by the arrival of the Marines...Mook Horror Show results on a mass scale. It only becomes more terrifying when Vinci forcibly awakens the Haunt-Haunt fruit and uses it to start building Prometheus, which causes the already twisted reality on the island to go completely insane.
- Prometheus is a Sapient Ship, and the ghost that haunts it is a fairly nice guy in general. It doesn't stop the ship from being a massive, immensely creepy Ghost Ship filled with monsters, corridors that move on their own, and inexplicable hazards.
- INCUBUS. Just...INCUBUS. His very presence is immensely creepy.
- Vinci is normally a Bunny-Ears Lawyer guy who, while off-kilter, isn't particularly evil. When he stops being The Fettered, though...people on the wrong end of his anger can only describe him as inhuman, and he dips deep into the Uncanny Valley.
- The bell recovered from Fiddler's Green is in a class all its own, with it apparently attracting the attention of Eldritch Abomination monsters of some sort when sent world-walking, and possibly being haunted. Or cursed.
