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.

  • 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.
  • Most of Rise of the Runelords, with a generous side order of Squick. Special mention goes to The Hook Mountain Massacre (part 3), which turned the comically bumbling D&D ogres (traditionally just sword-fodder for guys who'd mastered killing orcs but weren't ready to kill giants) into beings truly worth of the Always Chaotic Evil label.
  • 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 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.
  • Kytons, in Dungeons & Dragons, were traditionally a minor fiendish race of minimal importance, chain-wrapped gaolers who dwelt upon the Lawful Evil plane of Archeon. In Pathfinder? Kytons are a race of sadomasochistic artists of Body Horror, Cenobite expies who rule the Plane of Shadow.
  • 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 it's 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.
  • Occasionally mention is made of the Dominion of the Black, an intergalactic empire that tends to view humanoids as a handy collection of spare parts. Most of what they use come from planet-sized slaughterhouses known as fleshfarms. They're particularly fond of brains, and genetically engineered an entire species to harvest whole brains for them. It's generally agreed that if they ever really decide to start playing attention to Golarion, the planet is pretty much screwed.
    • They get more elaboration in the Iron Gods campaign, and it gets worse. They are masters of disease and genetic manipulation to the point that they scare the freaking Mi-Go, when those are supposed to be their hat. They run entire planets dedicated to harvesting psychic energy from disembodied brains, like The Matrix but less humane, and when their Living Ships arrive they CRASH them and leave them alive to go insane as they rot. And they worship the void, to the point that their idea of a religious festival is to put a psychically chanting fleet in orbit around a black hole, as the most devout THROW THEMSELVES IN.