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.
- 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 Supersoldier 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.
- 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.