100 Most Dangerous Things on the Planet. Exactly What It Says on the Tin. It contains actually helpful tips for surviving said things, but also nice information on things such as, say, cobras that spit venom at you, from two meters away, in your eyes, the sentences "Dogs are everywhere. You should always see them as a potential threat", and my personal favorite, supervolcanoes. There's one under Yellowstone National Park. If you're in a 100km radius, you're screwed. Helpful hint box (paraphrased): "Don't panic! You can't do anything against them, so you don't need to worry". Yeah, thanks, guys. Oh, and it's aimed at kids.
Neil Gaiman's short novel Coraline was specifically written for this purpose (the idea of coming home to people who look like your parents, but aren't). And now Henry Selick, director of The Nightmare Before Christmas, has turned it into a movie.
Apparently, according to the man himself, kids come up and tell him that they read it kind of like they would read an adventure story, whereas their parents would go around the house and turn on all the lights.
The movie actually increased the Paranoia Fuel with a doll that acts as the Other Mother's spy. Said doll can change appearance, move around when you're not looking, and the Other Mother can see through its (button) eyes. Sleep tight.
While we're on the topic of Neil Gaiman, let's add American Gods to the list. The world is ruled by selfish gods who feed off of our beliefs and treat humans like a commodity. And, in the protagonist's own words: "They get to break all the rules they want. We don't. Even if I tried to walk out of here, my feet would just bring me back." It's not surprising at one point, he voluntarily chooses non-existence over spending the rest of his afterlife with them. The gods have other plans for him...
Neil Gaiman also wrote a short story called "Foreign Parts" in which a venereal disease (in itself a real-life example of this trope) actually takes over the main character's personality. It's even implied that he didn't even catch it from having sex.
In Jurassic Park's sequel, The Lost World, this definitely applies to the Carnotaurs. They're dinosaurs with nearly perfect camouflage who live in the area of the gas station waiting to ambush prey. The human characters pass by their territory several times without realizing the predators are there, and it takes a lucky switching on of the lights for Thorne to realize that they are right in front of him. Not even the Velociraptors or the T. rex will enter their territory unless absolutely necessary.
Book 3 of The Dark Tower series, The Waste Lands, features an example of Paranoia Fuel combined with nightmares in the story, in the form of Charlie the Choo-Choo. Despite being a children's book, this story gives Jake, Susannah and Eddie the creeps when they first read it. Jake imagines that beneath the sugary sweetness of the story, the titular character is evil to the core, which foreshadows the Ka-Tet's encounter with Blaine the Mono at the end of the book and the beginning of the next one. Given the illustration of Charlie◊ that some editions of the book have, it's hard to disagree with Jake's instincts, what with the evil grin on Charlie's face and the children on the train apparently screaming in terror.
King is pretty well known for this; there's a reason the Family Guy parody of him said he just takes household objects and makes them creepy. You know that world-ending virus that causes coughing, phlegm buildup, delusions and eventually death in The Stand? It's specifically described as indistinguishable, in the early stages, from the common cold or flu. 99.4% of people exposed to it catch it and die. Yes, that's right, you have slightly better than a one in two hundred chance you'll be one of the survivors on a lifeless, forsaken planet. Oh, and it can be transmitted just by walking past someone with it.
Discussed in King's notes on 1408. King states that hotel rooms are inherently creepy due to the fact you have no idea who else has come and gone from them before you came, and who will come and go after. Any number of those people could have been sick or insane at the time they stayed, and several of them have probably already died.
Then there's Apt Pupil. That nice, folksy old guy who lives on a quiet little street? Yeah, he's a horrendous Nazi war criminal. And the seemingly normal boy next door wants to be just like him.
And The Bogeyman. The idea is simple: The monster in your closet is real. And it will kill you.
Strawberry Spring: Split personality disorder and a horrifying ending as the protagonist realises just what he's been doing over the years.
IT: Every fear you've got come alive with malicious intent. He even managed to make beer scary.
And then there's "Quitters, Inc." It delivers the deliciously warped aesop of "Be healthy or we'll kill you."
And "Stationary Bike" has the Aesop of "Not too healthy..."
Dreamcatcher will keep you from ever going into the woods again.
Cujo will almost certainly give you an aversion to St. Bernards any big dog, EVER.
And then there's bloody Cell. Everyone who uses cell phones goes berserk and acts like a rabid dog on steroids. Since everyone uses cell phones these days... yeah. Sleep tight.
Also, the story the Ten o'Clock People from Nightmares & Dreamscapes. If you smoke, I can practically guarantee you that, after reading this story? You will find that the only form of quitting you might think about is Going Cold Turkey. Otherwise... you might see THEM!
The kid's book L'enfant et les sortilÃ¨ges / Boy and the Magic, made after the opera by Colette. Content: When a little boy destroys some things in his home - a clock, a teapot, a cup, a wallpaper with figures, his homework - they all come alive (even the numbers from the math book!) and are very angry at him. Definitely NOT recommended for kids who don't fully understand the world yet.
A science book: The Life that Lives on Man, published in the States for the first time circa 1977; the best bit was the snarky 60s-70s era tone. It's not surprising to learn about skin flora, but it is surprising to learn that at one point there was actually such a thing as a flea circus. Also, did you know that follicle mites live in your eyelashes? But apparently they're beneficial or something somehow, or at the very least mostly harmless, and they take up a niche much nastier things could otherwise fill.
This is parodied in a host segment in Mystery Science Theater 3000, when the 'bots are as creeped out about Mike's eyelash mites and send the Nanites in to destroy them. A bloody war is fought and the mites are vanquished... causing random debris to build up around Mike's eyes. The segment ends with Tom and Crow expressing their disgust and saying he should really do something about that, and violence only being cut off by Movie Sign, as usual.
There's also a device called a translator that makes whoever uses it borderline omniscient. In the second book, it's revealed that this information includes nuclear codes and weapon stores. A translator user could use this information whenever they want.
The Witches by Roald Dahl. Any kids who read it will learn to be terrified of women with gloves. Dahl knew exactly what he was doing, too, because he takes a break during the introduction to speculate that teachers reading to their students might actually be witches, so take a look at her nostrils to see if they've got the scalloped edges. (He also says that your lovely teacher might be smiling as she reads it, which she probably would, knowing what he's up to. All presuming the teacher is a woman, of course.)
The BFG - there are giants that can run anywhere in the world in a single night. They reach through your window, snatch you from your bed as you sleep and eat you. Mummy, can I have bars on my window?
Despite knowing it is a parody (sort of...), The Illuminatus! Trilogy has still made readers paranoid enough to see conspiracies and The Illuminati everywhere in life these da- OH DEAR GODS THEY'RE PROBABLY HERE TOO! Don't see the fnords don't see the fnords.
Animorphs. Imagine reading those books when you were about 10 or so, and going to bed thinking about how anyone, from your best friend to your parents, could be controlled by mind-slugs, and you would never, ever be able to tell the difference- until they caught you and took control of your mind. Imagine: not being able to stop reading, because you think there'll be information there that'll help you to survive. All the while, not being able to go to anyone for help (because they'll tell you it's a fictional book)- because they'll drag you to the Yeerk Pool- kicking and screaming.
Harry Dresden from The Dresden Files: "Paranoid? Probably. But just because you're paranoid doesn't mean there isn't an invisible demon about to eat your face."
He Who Walks Behind is an Eldritch Abomination whose distinguishing characteristic is that when it manifests it is always behind you. Even if your back is against a wall, it's still behind you. And now it just has a handy solid surface to pick you up and strangle you against. With one of it's tentacles around your neck. Which it didn't have in the reflection you saw of it.
Blit, a sci-fi short story by David Langford. In essence, modern-day mathematicians discover a certain pattern which can kill you just by looking at it. Various terrorist groups paint it on walls to kill whoever is unlucky enough to wander by. Ever tried not looking at walls for a few days?
Read the companion document, "comp.faq.basilisk". Do you use an HTML email viewer with embedded images enabled? Imagine being sent something a bit nastier than goatse...
In The Metamorphosis, a man wakes up to find that, for absolutely no discernible reason, he has turned into a giant beetle.
In The Trial, the main character goes through a trial in a Kangaroo Court, without ever even being told what he is accused of.
"Examination Day," a story by Henry Slesar that was first published in 1958. It involves a character being told by his parents that he is to take a government sponsored test. At the conclusion, the government official tells the parents that he was too intelligent and thus executed, and asks whether she wishes for private or government-sponsored burial. Think about that. If you grew up in the United States school system, you've been taking standardized tests since you were six. Then SAT's, ACT's, IB's (bonus points for being an international conspiracy), AP's... And they are unavoidable. Puts a new spin on No Child Left Behind, doesn't it?
Any and all books by R. L. Stine, especially Goosebumps, Nightmare RoomWhen Good Ghouls Go Bad and Shocker Street.
The ending to Werewolf Skin, one of the last true Goosebumps books. In it, you and your new best friend discover that a large portion of your new neighbors, as well as your aunt and uncle who you're living with, are werewolves. In the end, you and your friend free your aunt and uncle from the curse, only for your best friend to reveal that she has turned too...
"The Haunted School", in which a small school's students in the 1940s end up trapped in a permanently monochromed version of their one-room school by a sinister camera guy, doomed never to age or die, and never to see colors of any kind again. And you can sometimes hear them behind the walls in real life. And then the exact same camera guy is still alive fifty years later to take a picture of a group of students working on a big school party.
The Mr. Men stories have this in the form of a character called Mr Tickle who has reeeeeally long arms that he can use to reach hard to reach places and to tickle people with- the worst thing is... He could appear anytime and anyplace and his long arms could reach out and get you.
That's like saying that the Care Bears can see you when you're sad and come down from that fluffy place in the clouds that is Care-A-Lot to cheer you up tho... On the other hand, don't.
The later books in A Series of Unfortunate Events present a massive Ancient Conspiracy which "recruits" "volunteers" by kidnapping them in infancy (although sometimes they ask the parents). This conspiracy is divided into two warring factions, which are indistinguishable in practice not only due to Black-and-Gray Morality, but because they use the same disguises and codes. The Lemony Narrator (himself involved in the conspiracy to some degree) strongly implies that the reader's own teachers, librarians, and family members could be part of it.
House of Leaves was made of this. You will never look at your house the same way again. Is that wall just a bit further away than it was yesterday? Was that door always there? Is it just a bit colder than it should be? Whatever you do, don't look behind you... Did you look?
But do make sure you measure the dimensions of your room. And your house. In case they don't match up. And check again later, in case they've changed.
This is part of what makes the works of H. P. Lovecraft and many Cosmic Horror stories so effective; the idea that our stable, comfortable reality is merely a temporary, fragile illusion behind which lurk any kind of unknowable horrors way beyond our comprehension just waiting to completely shatter us. The Gods, if they do exist, don't care about us in the slightest... which, considering what happens if they notice you, is a good thing.
Everything by Thomas Ligotti. Everything becomes horrific. Pills, paperwork, libraries, flowers, chamber music, horror stories... Reality itself is the main source of terror in most of his work. In short, the Anthropomorphic Personification of this trope.
That's Incurable!, by George Thomas and Lee Schreiner. One entire chapter is deliberate Paranoia Fuel. The chapter title? "Ten Diseases You Were Better Off Not Knowing About". Some of the diseases are communicable, some genetic, and some hadn't had a cause isolated as of 1984, when the book was published. But the three things they all had in common made it blatantly clear that the chapter was intended as Paranoia Fuel:
They are rare.
They are real.
They begin with innocuous, everyday symptoms...
Similarly, The Hypochondriac's Pocket Guide to Horrible Diseases You Probably Already Have (it starts with Gigantisim and gets worse - and yes Candiru are included) and its sequel The Paranoid's Pocket Guide to Mental Disorders You Can Just Feel Coming On, which was worse for the author to write due to being an actual neurotic:
The author: I always believe myself to be healthy physically, but mentally, I'm a hopeless, blathering, soggy wreck. [...] The fact, alone, that I subjected myself to several months of research into mental disorders that I felt on the cusp of acquiring (emphasis not the author's) bespeaks some sort of unhealthy masochistic tendencies.
An unknown word that, if said, will drive you mad.
Foundations: A man is plagued by the voice of the foundation of buildings and must kill people to appease it. "-we are hungry. we are hot. we are full but hungry"
Different Skies: What you see out your window may not be what's really on the other side of the wall.
"Details" can make everything (everything!) terrifying since there's a monster that travels through the patterns around you and, once you see it, you can never unsee it, and it will try and absorb you.
"The Tain"- your reflection wants to kill you! And take over the world!
The skin-spies in Second Apocalypse. They can physically mimic anybody, almost perfectly. They're inhumanly fast and strong, and can kill you with one hand. They might be your friend, your king, your lover, but it's impossible for a normal human to tell.
The Plant People, a short story by Dale Carson in Bruce Coville's Book of Aliens, detailed a mysterious fog filled with dancing lights that slowly turned people into cacti. It seems silly until you read about them first changed into brainless, green-veined shells of their former selves, wandering listlessly around trying to photosynthesize, and see the illustration of one confused victim clutching a cactus, not seeming to mind the pain. Worse still is the end: A news report says they finally found a cure, but just as they're about to reveal it, the fog descends...
Philip K. Dick infuses this into all of his work. The characters in his stories have their paranoia stoked by things ranging from subtle to jarring, and it is often unclear whether the cause is a conspiracy, their own insanity, or a breakdown of reality itself.
Biography of the author suggests that much of this paranoia was drawn from his own life and his unique mind. Dick likely suffered some degree of paranoid schizophrenia. He was smart and self-aware enough to know that his perceptions might be warped, but was never free of the suspicion that reality was disintegrating around him. This lead him to write with equal intensity in the genre of science-fiction and the spiritual field of Useful Notes/Gnosticism.
In "The Father-Thing," a little kid discovers some alien thing has killed his father and is walking around in his skin. Nobody else notices the difference.
In another story, researchers land on an alien planet full of beings who are trying to kill them and can shape-shift into anything. One character is attacked by their microscope, another by their rug. "My wife gave me that rug, I trusted it completely!"
Lullaby by Chuck Palahniuk. There's a lullaby that's an ancient killing curse and it kills anyone who has it read to them. It was printed as a nursery rhyme in a popular children's nursery rhyme book. You could kill your kids accidentally by reading it to them. Easily. In the story, there are a few people that have used the song so they can kill you just by thinking the song at you. Oh, and you don't even have to know the person. They might hear your voice on the radio, decide you're being annoying, and boom.
Dementors, wraith-like monsters who drain your happiness and potentially suck out your soul. Not good enough? They're invisible to muggles like you. You know that shivery feeling you get down the top of your spine as you read this page? That feeling of dread, growing larger and heavier in the pit of your stomach? That's what dementors do before they even attack. Then they make you relive the very worst experiences of your life (and, them being invisible, you have no idea why your mind seems to be driving itself to suicide) and the very last thing you feel is their cold, desiccated mouths on yours as they suck your soul away. And then you feel nothing at all.
What's worse than Dementors? Lethifolds, the equally evil species-cousins. They eat you alive, and there's no way to stop it unless you cast the patronus charm. You don't feel it until you are already dead or notice you are missing skin. Since they're invisible to muggles and only attack sleeping victims, they could be anywhere.
Even worse, there's a sociopathic, nigh-invincible Dark Wizard that can kill you in more ways than you can count on the loose, and guess what? If you even SAY HIS NAME, he can find out instantly where you are.
Legilimency. The idea of someone intruding in your mind is pretty creepy.
Might as well add the other forbidden curses— the Imperius and Cruciatus curses. One can turn you into the user's puppet with a single word, and the other one can torture you horribly (even to the point of insanity) without leaving any marks.
Rita Skeeter. The creepy part is that she does her spying in the form of a bug.
Polyjuice Potion also deserves mentioning, allowing the user to impersonate any human...
Wizards can do what they like to you and then make you forget. Except with too many memory wipes, or even just one that goes a bit wrong, you suffer brain damage. And it's standard government policy to mindwipe anyone who sees anything magical. Oh, and if they use an invisibility cloak or a Disillusionment Charm, they could be standing right there. And until 1996, the British Ministry of Magic was employing the invisible depression-causing soul-eating monstrosities, and, if someone important and corrupt wanted to have a bit of fun, or to eliminate a troublemaker and didn't care about collateral damage, they could be sent out. And everything to do with these people is hidden from us. Have fun sleeping.
One fan theory suggests that there are no muggle-born wizards or witches, but there are some evil wizards, armed with Imperio and Obliviate.
Prisoner of Azkaban introduces us to Animagi, wizards who can turn into animals. At the climax, it's revealed that the big villain of the book, Peter Pettigrew, managed to hide out as the Weasley family's pet rat Scabbers for twelve years after killing twelve Muggles. Yep, so for all you know, your pet cat could be a crazy mass-murderer. Good luck sleeping after that.
Some of the scariest books in R. L. Stine's Fear Street series might be the ones that don't contain any supernatural occurrences, but have the protagonist's best friend turning against him or her, and trying to kill him or her.
Flowers in the Attic by V. C. Andrews could cause children to worry that their own (seemingly affectionate and caring) parents would turn against them, and try to kill them. The part where the Grandmother drugs and pours tar into the protagonist's hair while she's asleep is somewhat paranoia inducing.
Reality Check by David Brin. Apparently, eternal life is so boring that the protagonist voluntarily entered a Lotus-Eater Machine, and someone is now trying to wake him/her up. You're the protagonist, and the story is your wake-up call. The tone becomes increasingly urgent as you demonstrate yourself "unable or unwilling to scan the text for embedded code with the scanner in the blind spot of your left eye."
John Dies at the End by David Wong. What if they've taken someone you know, or used to know? Maybe they're around you right now. Maybe they're you.
Various stories in David Lubar's In The Land of the Lawn Weenies, but in particular, The Slide. You know those tube slides on playgrounds? Well, what if one of the support tubes holding it up actually leads down to a giant, insect-queen-like thing that spews out quasi-children thrown straight out of the Uncanny Valley, and if you go down that slide, you'll fall into the tube and become the food source for the 'mother'? And said children are going to actively try to force you to go down said slide? Lubar seems to enjoy taking normal childhood games and experiences and turning them into pure unadulterated versions of this trope. Did you ever try to walk around with your eyes closed for fun as a kid? Hope you didn't get sucked into a horrible alternate dimension and transformed into a screeching monstrosity unable to reverse the process and get back to your own world because you have no eyelids!
Hyperion Cantos. Merlin Sickness causes you to age backward in time, meaning that every day you wake a day younger, having lost a days worth of memories. So, immediately after you contract it, you'll wake up not remembering what had be to befallen you; someone will have to explain it. And then the next morning, they'll have to explain it again. And again. And Again. And Again.And Again. Over and over, every day until you either die or age back to before you were born. Initially, this task will be handled by doctors, but as time passes this grim chore will pass to your friends and family. But with every passing year, more and more of your friends will have to explain to you who they are, because you will no longer remember meeting them. Eventually, you will forget all of them, and be forced to rely solely on family for the daily explanation of what's happened. But then your family members will start to die, and the survivors will have to inform you of this every day. This daily task will wear upon them, until finally they give up, and stop telling you. And then you will have to face the world each morning scared and alone, confused as to why the world has suddenly changed so drastically while you were sleeping. And each night shall erase the memory of this, forcing you to face it anew each day. Have fun getting out of bed tomorrow morning.
This disease is similar to the real-life syndrome anterograde amnesia, one victim of which is Clive Wearing. Imagine, being a brilliant musician one day, catching a disease that destroys a large part of your brain and then waking up with a memory that resets itself every 30 seconds or so. Imagine never knowing where you are, how old you are, what time it is or who you're with. Imagine having to live this way for the rest of your life.Shudder.
Short Russian story "Spell of Body Spirits" by Lleo Kaganov. It describes a text engineered in such a way that it critically affects the brain of any reader. After reading it their body ceases to function properly, which naturally leads to their demise. Obviously, the protagonist has already seen the text by the time he learns about it - and the reader of the story with him. The funny part? The text of the story itself is constructed using psychosomatic techniques which lead to feeling the described symptoms, such as shortage of breath, raised heart rate, constant yawning and so on. It's not like you would be afraid that one day a seemingly random set of words could kill you. You would be worried if you are going to die withing hours.
The Andromeda Strain is about an outer-space virus that kills everything. And it mutates with every growth cycle. And setting off a nuke would just make it stronger.
Airframe. An airplane has a midair incident which injures dozens of passengers and kills three. It has safety precautions to prevent precisely such an incident, and the pilot was highly trained. Turns out he left the cockpit for about a second and let his inexperienced son fly the plane. And this could actually happen.
The Cobra Event by Richard Preston. Good luck reading it without running to the bathroom to see if there are yellow rings around your eyes. Yellow rings + cold symptoms = infection. Infection = congratulations, soon you will be eating yourself. His other two virus books, The Demon in the Freezer and The Hot Zone are even worse. Because the events in those books are real. Just try reading them without periodically having to remind yourself that the head ache your feeling isn't the beginning of your brain liquifying.
The Pendragon Adventure: Saint Dane. Anyone could actually be in disguise actually manipulating you to cause the destruction of your world all while making you believe you're helping people. Even the bully you've grown up with since childhood. It's also implied that he followed Aja her whole life in different forms to manipulate her into creating the device that completed his plan.
Warrior Cats. What do your cats think about? Do they hate your guts? Are they actually the Hitler of their world, or a mass-murderer? Or worse... are they plotting to kill you? After all, a cat with Scourge's claws and temperament would probably find it all too amusing to slit an unsuspecting human's throat as they slept.
The idea of the Dark Forest is this, too. Even after your enemies are dead, they can still kill you in your sleep. Also, they could be training your friends to kill you in their sleep.
Possibly even worse is Tailchaser's Song, a similar book published in the mid-80s. The basic premise is the same, but instead of just fighting particularly violent cats, the protagonists battle morbidly obese cat gods and their army of demons that kidnap people from under rocks and eviscerate and eat dogs.
The Watertower by Gary Crew. It's a Australian childrens picture book about a kid who dares his friend to go into an old creepy water tower. The layout, the imagery and the atmosphere makes it far more unsettling than any childrens book has a right to be. By the end, we never find out what happened in the tower, only that something was in there. Something that can possibly infect people. Most of Gary Crew's other novels / stories aim for a comfortable residency deep in the heart of Paranoia Fuel territory.
In The Godfather novel, but let out of the film, was a scene of Woltz after finding his horse's head on his bed. Woltz starts to think of revenge on The Mafia, still thinking that he's superior to them. After all, he was the one who refused An Offer You Can't Refuse. Then he thinks twice and realises that if The Mafia could sneak onto his grounds- into his bedroom, and do what they had done, what else could they do?
Fablehaven. If you're not family or a long time friend, you're an enemy. That guy who saved you from the hobgoblin? He's using you to steal artifacts. The woman who saved you from him? Using you to build up trust to steal a key to a demon seal and kill you all. The man you worked under for a year who runs the daycare? He just got cloned and is going to ship you off to a vampire now. Oh, and one more thing. Those fish, they're really naiads. You can't tell because a magic veil makes them look like regular animals. If you get to close they'll pull you under, it's fun to see you drown. What pretty little fish.
Neuropath. People are working on ways to control your brain, and there's nothing you can do about it.
An in-universe example of Paranoia Fuel is "stealth chess", a variant of traditional chess played at the Assassins' Guild in Discworld. Each player has two extra pieces (Assassins) that move up and down two extra rows at the sides of the board, can spontaneously leap out and attack any non-Assassin piece in their range, and may not actually be where they seem to be. The game is designed to foster paranoia in Guild students who play it.
After by Francine Prose. The rules are always changing, break one and it's a one way ticket to 'Operation Turnaround' [read: your grave]. What might some of these rules be? Did you have a cell phone on your person at school? What about gum? Anything red? Did you eat lunch alone? Oh, and Big Brother's watching you. And by watching you, I mean really watching you. Yes, even 50 miles away. Remember your sweet history teacher? The one who didn't report that sweet, A++ girl who broke a rule? Yeah, she had a "Health Emergency". And don't expect your parents to help you, they've been brainwashed. Everything is for your own good. And they could come for you at any time- right in the middle of a normal school day, even if you've done nothing wrong. Have fun at school, dear.
Jeff VanderMeer's Ambergris-books: There is a race of interdimensional midgets living beneath the sewers, who observe your entire city through ubiquitous fungus spores, and they manipulate people's behaviour with different spores that you breathe in or eat with your food, that affects your emotional balance and behaviour. Everything underground is their realm, not even your own cellar is safe if you stay down there too long. Oh, and they can walk through the walls. And they plan taking back over the city that was once taken from them.
If you were a fledgling in The House of Night you would never know that your body is rejecting the Change, until you start coughing up blood. Then, in about 10 minutes, you would be dead and then there's nothing that anybody can do.
Honor Harrington: In At All Costs. After an assassination attempt that was thwarted by milliseconds, the Star Kingdom of Manticore gets rather jumpy about how the assassin was compromised. He wasn't. As the audience knows and Manticore doesn't even suspect, the people in question were hit with nanomachines, which can be delivered in food, or water, or that window-cleaning junk the driver of the taxi you took just sprayed on you. And the victims are fully awake as they watch their body kill others, or even themselves. That is if they aren't doing lovely things like altering your memory and making you think things are perfectly normal. Such as that salesman in the throne room with the "perfume" that's actually binary nerve gas.
"Jeffty Is Five" by Harlan Ellison. Imagine, for a moment, that your child is Jeffty. He is five years old, physically, mentally, emotionally and developmentally though chronologically he is much older. Because he is still five you have to take care of him, as long as he is five which may be for the rest of your life. Now that may not seem so bad on the surface but then you add in the fact that even more impossible stuff happens around him. He keeps getting new issues from magazines that went out of business. He keeps watching new episodes of tv shows that were cancelled years ago. And to top it all off, you can do absolutely nothing about it, nor can you tell anyone. Now who feels like never having children ever? It Gets Worse when Jeffty gets beaten up by some older boys at the cinema while the narrator isn't around to look after him. And then Jeffty's mother is driven to murder Jeffty just to live in the present again. This story is light for something by Harlan Ellison.
The premise of the Moon Crash Series by Susan Beth Pfeffer. At the beginning of the first book, Life As We Knew It, everyone knows about a meteor that's going to crash into the moon, but no one thinks much of it. Then the crash does happen and the impact is enough to knock the moon closer in orbit to the earth, causing tsunamis, earthquakes, and enough volcanic eruptions to cloud the sky with ash and block sunlight, causing famine, temperatures below freezing, and death. The scary part? It's perfectly possible for a meteor or asteroid to crash into the moon and it's happened before, as evidenced by the multiple craters on the other side. And it could plausibly have that effect.
In The Bartimaeus Trilogy, spirits are summoned from an alternate plane of reality and used by magicians to perform their magic. The titular djinn helpfully informs the reader that these spirits are generally invisible to commoners, and...
...there's probably something invisible with lots of tentacles hovering behind your back right NOW.
Invoked by Deacon in Tunnel in the Sky, when the survival-class instructor gives his students a parting warning to beware of stobors as they set out on their field test. He doesn't tell them what a stobor is, and indeed doesn't know about any such himself: he just says it to make sure they'll be wary of anything new and potentially dangerous they might encounter.
In Pure, by Julianna Baggott, not adhering to social conventions by, say, not going to church, can get you put in the loony bin. The government can and will alter your behavior, plant a bomb in your head and bug your eyes and ears, and you won't even know until it's far too late.
The Laundry Files. Case Nightmare Green. In just a few years a host of eldritch abominations are going to break into our reality and eat our brains. The government knows very well what's coming, and they can't do anything about it. And neither can you. There's also the problem of magic = applied mathematics. The series protagonist, Bob, was recruited by the Laundry because he accidentally wrote a program that would have unleashed Nyarlathotep on an unsuspecting Wolverhampton. Now think about how many hackers, viruses and assorted crapware programs are out there. A tentacle emerging from your shiny new Droid to strangle you is the least of your worries.
Mistborn: The kandra. They can be hired by anyone, are bound by contract to do their job, and can take on the form of anyone dead. So your family members could be killed and have their bodies eaten and imitated by kandra and you wouldn't even know it. Kandra are also great actors, and people being impersonated are often tortured before they're killed to learn information about them and prevent Bluff the Imposter. Also, in the later books, Ruin. He can hear anything spoken and see anything written down unless it's written on metal. He can also change anything written down if not written on metal, is a master manipulator, and, if he can get a hemalurgic spike into you, he can manipulate you with voices in your head and change your basic urges and instincts. He is everywhere. And what's his goal through his manipulation? To cause the end of the world. *shudder*
Deltora Quest has the Ols. Evil, monstrous shapeshifters that serve the Shadow Lord, they are very difficult to kill and can kill you instantly. They come in varying Grades of quality, each one able to increasingly able to mimic their chosen shape and increasingly hard to identify, with the most advanced Grade able to perfectly imitate all human bodily functions and emotions, perfectly mimic the personality of anyone they spend enough time around, lack the Glamour Failure that is the only reliable way to identify them, and can even mimic inanimate objects. Anyone you know, anyone and anything you see could be an Ol waiting for the perfect moment to strike...
The Evergence trilogy has the Sol Wunderkind, a race of super soldiers physically and mentally superior to humans, but otherwise outwardly indistinguishable from them. Their goal? The extermination of the human race. But to do that, they've first infiltrated human society and disguised themselves perfectly, to the point that only powerful psychics are capable of telling them apart from normal people. They could be your friend, your coworker, your lover; you could have known them all your life without ever suspecting a thing. And then one day, without warning, they'll coldly murder you and everyone around you without hesitation or a shred of remorse or regret.
In The Fifth Wave by Rick Yancey, the Silencers look exactly like humans, act exactly like humans. And then they kill you.
One doesn't have to be a rocket scientist to figure out that the situation in The Prophet of Yonwood (the U.S. battling a terrorist nation that threatens total war) is a natural progression from what the world is going through today.
In The Wee Free Men, Tiffany frequently has to contend with dromes: doughy creatures that spin dreams the way spiders spin webs, trapping people inside and watching them dream and eat dream food until they starve. Tiffany thinks how dangerous it would be if they got out of Fairyland to the real world, turning life into a nightmare and warping your perspective until you wanted to die. Then she immediately changes the thought to I wonder how many have got in already and we don't know?
The Maze Runner books really push the idea that everything that happens is actually one of WICKED's machinations, making one wonder how one would feel if one's life was also entirely managed by unseen Mad Scientists. It doesn't help that, by the end, everything that happened was pretty much what WICKED, or at least its leader, wanted anyway.
2666: The Parts about Amalfitano, Fate, and The Murders run completely on this. Hundreds of women are being brutally murdered, the killer could be anyone, and the police and mayor's office are likely in on it.
The Thrawn Trilogy: Thrawn, as might be expected, excels at weaponizing this trope. One of his more notable achievemnts using this trope was having a bunch of cloaked asteroids thrown into orbit around Coruscant, while simultaneously having his ships run power surges through the tractor beams. The result is that, out of the over 200 power surges, the New Republic has no idea how many of them were actual asteroids, and they can't risk sending out ships, since there's a fair chance they'd bump into an invisible rock.