Nightmare Fuel / Pathfinder
Seventh Chronicle of Saint Ferais, Dragon Slayer 

Pathfinder is much Darker and Edgier than most Dungeons and Dragons-based worlds, and it SHOWS.

    Rise of the Runelords 

Paizo’s first Adventure Path set the (dark and edgy) tone for all Pathfinder stories to follow.

  • Burnt Offerings
  • The Skinsaw Murders
    • The fate of the Skinsaw Man’s victims, especially Katrine Vinder and Banny Harker. Both were subject to a Cruel and Unusual Death, and Harker’s body was horribly mutilated by the murderer.
    • Habe’s Sanatorium is a Bedlam House run by two Mad Scientists and their hired tiefling thugs, and its occupants include a crazed, blade-obsessed wererat and a man well on his way to becoming a ghoul.
    • Your Lordship’s handwritten notes to the PC he’s obsessed with. Whether he’s a Yandere, a Green-Eyed Monster, or hell-bent on murdering you, knowing that the murderer wants ‘’YOU’’ is more than a little unnerving.
    • Foxglove Manor. You know a place is bad when the house isn’t just haunted, but a ‘’lich’s Soul Jar’’, albeit one created accidentally. In terms of pure horror (both in-your-face and the fridge variety), the haunts here (and their history) are only topped by the ones in Spires of Xin-Shalast. Oh, and did we mention the rats?
  • The Hook Mountain Massacre
    • Really, everything in this chapter. You want specifics? You really don’t, but if you insist…
    • The Graul Farm almost surpasses the ruin of Fort Rannick in terms of grotesque ogre antics. Almost. From the morbidly obese, necrophiliac and incestuous Mammy Graul; to the various ogrekin deformities; to the horrific and cruel traps; and finally, the giant freaking ogre spider they keep in the basement; the ogrekin of the Graul family give the players their first taste of the savage depravities of ogrekind.
    • The ogre attack on Fort Rannick, and the carnage the PCs walk in on. One ogre is making dough from the guards’ entrails, one wears a bunch of dead minks in place of his severed jaw, one writes graffiti using a beheaded corpse as a brush, one enjoys playing with the corpse of a cleric of Erastil, and there's the absolutely brutal ways that Jaagreth Kreeg maintains control over his clan. The PCs are given plenty of opportunities to Kick the Son of a Bitch; after seeing all this, they may very well take them.
    • The flood. Besides the danger of a young girl getting eaten by a gigantic snake, there’s also the sudden appearance of Black Magga.
    • The fate of Avaxial in Skull’s Crossing. The pit fiend has been trapped here for millennia, and his life force has been slowly draining away (in game terms, he has 19 negative levels; one more will kill him). And even if the PCs decide to save him (when it’s in their best interest to put him out of his misery), the text states that he may very well come back to murder them for finding him in such a humiliated state.

Everything Else

  • Lamashtu: Besides being a goddess of monsters and nightmares, there's all the horrifying details surrounding her progeny and worshipers. For example, Lamashtan priestesses who give birth to children blessed by their goddess do so by letting their offspring tear their way out of the womb.
  • More fun in this vein are The Motherless, Tieflings with Qlippoth heritage. They're implied to eat their way out in childbirth, with invariably fatal results.
  • Also Zon-Kuthon, god of pain, who preaches torture, mutilation (of both oneself and others), and dismemberment of living victims (who are kept alive as long as possible). Zon-Kuthon brutally tortured and flayed his own father until he was a broken and twisted slave.
    • And why is he such a monster? He is presumed to have met ''something'' which either corrupted or possessed him. Before that event, he was quite nice.
    • His champion as well, the great blue wyrm named Kazavon. He took over the Hold of Belkzen disguised as a human, then he went Vlad the Impaler on everyone. Besides that mess, there's the fact that, in a way, he's still alive. Bringing together the Relics of Kazavon will resurrect the dragon and... well, that's just one more way that Golarion is screwed.
  • Carrion Crown is a swift trip into the horror genre. What does it start with? A haunted prison, what else!
  • Scared of Hillbilly Horrors? Pathfinder takes the tropes and applies them to not one, but three kinds of giants.
    • First up, there's the Ogres, from their first appearance in "The Hook Mountain Massacre". They're hideously deformed, rampantly incestuous, sadistic, murderous, cannibalistic monsters whose "society" revolves around essentially nothing more than food, sex and torture. Their idea of games include mig-a-mug-tug (grab each other by sensitive spots and yank as hard as you can; first one to collapse in pain loses) and man-swords (smash two humanoids together until they've been crushed to a pulp). Their genes are so polluted that not only are "ogrekin" invariably distorted and grotesque-looking, the ogre's genes effectively destroy the bloodline — an ogrekin can mate with humans, but nothing in their family tree will ever resemble a human again. Worse still, the rampant inbreeding ogres practice can eventually lead to them devolving into "degenerate ogres", creatures so foul and hideous that even other ogres think of them as primitive monstrosities. To say nothing of the mutations that can plague given clans, like the Shaggras, whose whole bodies are covered in carpets of thick, greasy, rank Prehensile Hair.
    • Then there's the Hill Giants, who are less incestuous, but still rampant cannibals, brutes and barbarians.
    • The Marsh Giants, meanwhile, are believed to have been hill giants... once. Now they're something so foul even ogres regard them with fear. They basically practice all of the same horrors as ogres, but with their own horrors on top of it. For example, not only do females spend so much time chewing on toxic mushrooms to enjoy the drugged out states that ensue they invariably either neglect their children or retard them with their poisoned milk, fathers and mothers typically eat their children, since their barbaric form of animism preaches that offspring are parasites of the soul. They also worship Dagon, adding some Lovecraftian cultist action to the mix.
  • The Qlippoth are Pathfinder's answers to the Obyriths. They are horrifically alien elder fiends -so old that when the oldest race in the cosmos, the Proteans, started to explore the multiverse soon after their creation, the Qlippoth were already there- that once ruled the Abyss before the coming of demonkind — and they want it back.
  • Pathfinder explicitly includes many creatures from the Cthulhu Mythos as part of its settings. Hounds of Tindalos, Dimensional Shamblers, Gugs, Denizens of Leng and their Spider enemies, Moonbeasts, Shantaks, Nightgaunts, Shoggoths, Elder Things, Flying Polyps, Bholes... the list just keeps going on, and even includes some of the Great Old Ones and Outer Gods, like Hastur, Shub-Niggurath and Cthulhu himself.
    • And Bestiary 5 adds Deep Ones, of Innsmouth infamy. Deep Ones who are explicitly capable of granting divine spells when they grow powerful and big enough. It's even worse if you happen to be a hybrid-the good news is, you have free will and won't be forced into an Always Chaotic Evil alignment by your transformation into the fishy side of your heritage. The bad news is, that's because the transformation actually kills you-horribly-and then reformats your body into a Deep One who simply does not care about anyone you, the previous owner of its body, were close to, only their Religion of Evil. And it happens quite quickly, when you're 60. Oh, and it's implied they're the source of much of the aformentioned Marsh Giants' genetic pollution and mental degeneracy.
  • Kytons, in Dungeons & Dragons, were traditionally a minor fiendish race of minimal importance, chain-wrapped gaolers who dwelt upon the Lawful Evil planes of Acheron and Baator. In Pathfinder? Kytons are a race of sadomasochistic artists of Body Horror, Cenobite expies who rule the Plane of Shadow. And as they are now a major fiendish race, they now have a whole hierarchy of progressively more powerful, twisted forms, all the way to Kyton Demagogues.
  • Similarly, Pathfinder abandons the mercenary war-profiteering Yugoloths of Planescape for its own dark entities, the Daemons. Born as the embodiments of mortal deaths of all kinds — old age, murder, insanity, poison, pollution, etc — and ruled by the Four Horsemen of the Apocalypse, these Neutral Evil fiends have but a single goal. Stemming back to the very depths of D&D Character Alignment lore, these monsters want but a single thing: the extermination of all life. They want to kill all of the gods, all of the planar races, all of the mortal races — they just want to kill and kill until there's nothing left but their own kind. And then, when The Multiverse is empty of all life except Daemonkind, they will turn on each other until only a single last solitary Daemon survives. That Daemon will bask in the utter emptiness... and then kill itself, as with nothing else to distract it, the fiend's hatred of its own existence is all that it has left to sate.
    • To drive the difference between the yugoloths and daemons home; in D&D, demons and devils are mostly concerned with fighting each other and yugoloths will act as mercenaries for either side - while there's some suggestion they're the real puppet masters behind the Blood War, they're mostly an afterthought as far as fiends go. Compare Pathfinder's Daemons, who are so evil and so dangerous that demons and devils will put aside their differences with each other and even with celestials to fight daemonic threats.
  • We all know the Derro: Insane dwarf equivalents, they were already freaky enough to get even the Drow squicked out about them. When Pathfinder gets its hands on them, what more can it do? Well, for starters, it can make them degenerate expies of the worst interpretations of alien Greys, with luminous eyes and frazzled hair, complicit in cattle mutilation and kidnapping. And the worst part? Now, they live right under cities. Not to mention the unfortunate fact that those victims they return don't remember their own absence but for bad dreams...
  • The third-party book "Path of War" gives us the Black Seraph discipline, a fighting style where literally anything goes. Attacks include kicking enemies in the guts to make them nauseous, snapping their tendons so they can't escape, and launches a flurry of blows that will not only kill them, but mess up their body to the point where revival would be impossible as they are too badly mangled to survive. Now let's say it loud: Omae wa mou shindeiru.
  • Far out in space (but not nearly far enough) is a planet-spanning empire known as the Dominion of the Black. Even the Mi-Go don't go into the Dominion. These beings are creators of synthetic plagues and generators of monstrous aberrations who regard humanoids as a handy source of spare parts. Their usual method of space travel is to crash-land their living ships on the destination world and leave the ship to go insane as it slowly decays. They enslave worlds in order to harvest organs from fleshfarms or draw psychic energy from entire plantations of brains-in-a-jar. They worship annihilation as if it were a god - their religious festivals involve a fleet hanging around outside a black hole's event horizon, intoning hymns of praise as the most devout of the pilgrims hurl themselves in. So far, they haven't paid much attention to the technologically backward, undesirable planet known as Golarion. So far.