Uncanny Valley/Literature

Examples of in  include:

""She would be called very handsome, I suppose, and yet there is something about her face which I didn't like. The features are exquisite, but the expression is strange.""
 * Helen Vaughan from The Great God Pan, probably one of the first Humanoid Abominations in modern fiction. She is described as quite attractive yet . . . off.

"[Weston's] body did not reach its squatting position by the normal movements of a man ... [although i]t was impossible to point to any particular motion which was definitely non-human. Ransom had the sense of watching an imitation of living motions which had been very well studied and was technically correct: but somehow it lacked the master touch. And he was chilled with an inarticulate, night-nursery horror of the thing he had to deal with -- the man-aged corpse, the bogey, the Un-man."
 * Lampshaded in So Yesterday by Scott Westerfeld. A special effects whiz explains that the human face is the hardest thing to animate convincingly because humans spend almost all of their time reading faces. If it's even a tiny bit off, we won't accept it.
 * The villainous Gray Agents of Sean Cullen's Hamish X series of novels are described as being deep down in the Valley.
 * C. S. Lewis:
 * Took his readers to the Uncanny Valley in writing Perelandra, the second volume of his Space Trilogy: describing as follows how the alien-evil-spirit-possessed Weston appeared to the novel's hero, Dr. Ransom:

"Look at her eyes. I don't think she's using them to see you with. They're just beautiful ornaments."
 * Another example in the first book: as Ransom deals with the aliens of Malacandra, he finds that they become disgusting and horrible if he tries to think of them as strange humans, but perfectly admirable and attractive when he approaches them on their own terms.
 * Lampshaded in World War Z: Zombies don't blink. Not only is this creepy, it also means the surface of their eyes is never lubricated, leading to the eyes becoming scratched and opaque. Hence the traditional white eyes.
 * Name-checked in the Mercy Thompson novels. Mercy describes the vampire Marsilia as being in the Uncanny Valley, as she's unnaturally stiff and still and her facial expressions look like she tried to learn them from a book.
 * In the novel Skinned by Robin Wasserman, when people get into fatal accidents, they are usually uploaded into the body of an android-like thing. These people are shunned because they look too perfect. Though to be fair, that was probably only one of the unconscious reasons. There were several social and religious factors involved (Like messing with God's Will, these people didn't have a soul, were fakes and copies...)
 * This trope is all but Lampshaded with regard to the creature in Frankenstein, who may be the Ur Example. As described in the book, the creature looked much closer to human in Frankenstein: A Modern Prometheus than he does in most of his film incarnations. In the book, the eponymous doctor believes his monster to be a work of art before he animates it, but once it lives and moves, he sees how horrible and inhuman it looks.
 * Eldar are described this way in the Warhammer 40,000 novel Hammer of Daemons.
 * Some of the more human antagonists in the Cthulhu Mythos invoke this, particularly in descriptions of such things as the Innsmouth Taint. Neil Gaiman's take on this in "A Study in Emerald" inspires a subtle sort of pants-crapping unease in the narrator on seeing the body of a member of the German royal family.
 * One word: Innsmouth. They have a bit of an "off" look, like they're inbred.
 * The Vord Queen in the Codex Alera tries to act human and look like a Cute Monster Girl, but mostly just succeeds in making everyone, even Invidia, want to hide under a bed somewhere.
 * The queen of The Fair Folk in the Discworld book The Wee Free Men is described as looking subtly wrong, because she's too perfect-looking to be human. It turns out her entire body is just an illusion of what she wants the viewer to see.

"the alloy of humanity that softened the godliness of the youth was lacking in the features of the stranger, awful and immobile in their beauty."
 * Same with the Lords and Ladies, notably during the Queen's confrontation with Magrat when her glamour starts to fail.
 * Paolo Bacigalupi apparently has a fetish for girls who fall into this category. The most blatant is the titular character of The Wind-Up Girl, so called because she walks in a jerky manner like a wind-up toy. In-story, this is considered remarkably beautiful, but it's somewhat difficult to visualize how this could avoid falling into the Valley in real life. In-story, it sometimes does. It was also a deliberate design feature to make sure that the main character and others like her couldn't be mistaken for unmodified humans.
 * The human-animal things in The Island of Dr. Moreau by H.G. Wells. Just reading about those things is disturbing. Reading about how they're created even more so, as Wells goes into just enough detail about the processes to be even more freaky.
 * A Fire Upon the Deep. The female human protagonist is watching a transmission from her homeworld, which has been taken over by an alien with god-like powers. She can clearly see that the human being used as a puppet/mouthpiece is acting strangely, but the aliens with her don't notice anything wrong with him because they're unfamiliar with human body language signals that we notice instinctively.
 * The Harry Potter series uses the Uncanny Valley to great effect:
 * If a character acts odd (for example, Ginny's overall behavior in Chamber of Secrets, or teenaged Snape walking in a "twitchy manner that recalled a spider" in Order of the Phoenix), keep your eye on him or her. And then, of course, there is the Inferi, which deliberately invoked this trope (because there is absolutely nothing right with a walking corpse). The way Voldemort is characterized in the movie also invokes this trope.
 * Luna Lovegood is described as having wide, buggy eyes that she blinks less often than one normally would. It helps to augment her strangeness, though she's also a sympathetic friend of the protagonists.
 * Played straight in Neal Asher's Cormac novels with the Golem androids. Early in the series most Golem androids are absolutely perfect in their humanoid design, with god-like strength and god-like beauty. Humans are usually pretty disturbed by them in their perfection because it makes the androids feel LESS human, since real humans aren't perfect. Furthermore most non-combat Golems have inhibitors which stop them using their joints in impossible directions and from using strength far greater than even an enhanced human. Subverted when later models have purposeful imperfections (moles, limps, idiosyncrasies) to make them feel more human (but are still quite capable of tearing people, and other androids, limb from limb).
 * In Jane Eyre, Jane is the only person who recognizes that something is wrong with Mr Mason: "...I like his physiognomy even less than before: it struck me as being, at the same time, unsettled and inanimate. His eye wandered, and had no meaning in its wandering: this gave him an odd look, such as I never remembered to have seen. For a handsome and not unamiable-looking man, he repelled me exceedingly...".
 * The Strange Case of Doctor Jekyll and Mr. Hyde - as said by Utterson, Mr. Hyde gives the "impression of deformity without any nameable malformation."
 * In Gulliver's Travels, it is implied in Part II that Gulliver was found to be off at first by the Brobdingnagians although it can be argued that it completely falls into this trope because unlike most examples, it does not continue.
 * Occasionally this trope's effects are felt in Niven's Ringworld novels, as the many hominid natives fall short of being Human Aliens. Usually it's the ones that are already creepy (ghouls, vampires) which give people the willies when they move their shoulders more loosely than expected or are found to have too small a skull.
 * Also part of the reason our Abusive Precursors are so, well, abusive. Our social system is horrifically twisted due to its rejection of Protector-stage rulers, and we just smell so incredibly wrong.
 * Played with in the Gaea Trilogy, in which a race of obviously-nonhuman alien centaurs, for reasons that make sense in context, sport genitalia identical to those of humans. This single feature's similarity invokes the Uncanny Valley effect because the rest of the body is so strange.
 * In Robert E. Howard's Conan the Barbarian story "Shadows in The Moonlight", in Olivia's dream, even the demigod son has an inhuman touch, but when his Physical God father appears:

"... at last he [Quasimodo] said, shaking his heavy and ill-formed head,-- "My misfortune is that I resemble a man too much. I should like to be wholly a beast like that goat.""
 * Ford Prefect from Hitch Hikers Guide to The Galaxy is described as unsettling because he doesn't blink nearly enough and his skin seems stretched too tight on his face.
 * Scott Westerfeld seems to have a talent for creating things that are Uncanny with a capitol U.
 * The pretties from the books series Uglies; they're literally perfect with symmetrical faces and all, and they all look very nearly the same. Then there's the specials who add a whole new level of creepy with their "cold beauty".
 * An interesting variation presents itself with Quasimodo in The Hunchback of Notre Dame:

""There was warmth and there was beauty in her olive-skinned face, but except for the eyes, it was warmth and beauty that didn't seem to have anything to do with reality. It was as if her face were not a face, but a mask that she had worn until it had almost become a face. Even her mouth, which was a mouth to talk about, looked not so much like flesh as like a too perfect imitation of flesh, softer and redder and maybe warmer than genuine flesh, but not genuine flesh.""
 * Mostly averted in C.L. Moore's story "No Woman Born". When a noted dancer and actress has her brain transplanted into a robot body after a crippling accident, she is still able to convey the same sense of beauty, grace, and charisma as before, although she needed to practice moving and talking in her new body before presenting herself to the public. The scientists who worked on her new body decided to give her a blank metal face to avoid the almost-but-not-quite human effect and designed the body to be flexible enough to dance as gracefully she could before, and this is justified in that humans rely on auditory and kinesthetic cues such as voice, gait, and personal mannerisms for recognition, not just appearance. Only at the story's very end, when she lets down her guard for a moment does her voice start sounding flat and robotic, instead of resembling her original body's voice.
 * The short story Stairway to the Stars by Larry Shaw, has this concise explanation: "It -- he? -- looked almost like a man, and that only made the difference worse."
 * The Star Wars Expanded Universe gives us Xizor's assistant Guri, a human replica droid. He assures us she is anatomically correct. Let that sink in.
 * Abeloth can be anyone. She is Luke's ex-girlfriends. She wants to assimilate Luke as well. But Vestara can see through her disguises.
 * In Rick Griffin's Argo, androids are usually designed to look like Petting Zoo People to avoid this trope, so that humans would be less intimidated by them.
 * Kellhus from The Second Apocalypse. He is completely emotionless, lacks any empathy and is utterly, ruthlessly rational. He can manipulate people by perfectly simulating emotions and normal human interaction. However, at one point he makes a mistake with one character. He takes just a split-second too long to respond to a question, during which his face just goes utterly blank and all emotion leaves his eyes before suddenly smiling and continuing with the conversation. The effect is described as extremely disturbing.
 * Arsene in The Woman with the Velvet Necklace. At the start, she's an incredibly beautiful and graceful dancer. But when Hoffman finds her alone -- after he's gotten word that she was executed -- she moves in a strange way, like a puppet, and speaks in a flat, emotionless voice. She also doesn't react when a burning hot coal touches her foot, won't eat, and when she drinks a little champagne, the champagne trickles out from underneath her velvet necklace. It turns out,
 * In The Pale King, there is something very, very off about Shane Drinion. His odd speech patterns, lack of emotions, facial reactions, or sense of humor make him seem inhuman. There's also the fact that
 * Why is this cover for the Haddix book Turnabout so creepy, you may ask? If you didn't notice (some won't,) half of the face is young when the other is old, effectively creeping us all out.
 * Dashiell Hammett describes it quite well in The Dain Curse (1928):


 * Coraline: Some of the pictures in the novel - especially the picture of the Other Mother with a bug in her mouth.
 * Some of the pictures from Man After Man: An Anthropology of the Future have disturbingly human faces. The Aquatics are particularly disturbing, because the rest of their bodies look more like cartoon manatees despite their realistic human face.