Uncanny Atmosphere

An Uncanny Atmosphere is basically when the characters/audience get the feeling that something is wrong in their environment. They don't know exactly what's going on, but they do know that something is definitely wrong.

For example: character walks into an area and gets the feeling that something is wrong there. Maybe everyone is gone? Maybe the inhabitants are all brainwashed zombies? Or, everything seems fine at first. But slowly, the characters/audience start to feel an undeniable sense of wrongness in the atmosphere.

Intentional use of the principles of Uncanny Valley are often applied to setting and background characters to increase drama or hint at conspiracy. The colors are a bit off (The Matrix), the people are too nice (The Stepford Wives), everything is too clean or it's just too quiet. This may be a sign of a Crap Saccharine World.

Compare to Uncanny Village and Nothing Is Scarier.

Film

 * The Stepford Wives

Literature

 * HP Lovecraft was very fond of this trope. Whenever his settings weren't an Eldritch Location, there would still be a distinctly 'wrong' aura about them, which the narrators typically emphasized. Innsmouth was a prime example, with its dilapidated structures and fishy odor hinting at something horrible behind the scenes. Other uses include The Colour Out of Space and The Whisperer in the Darkness, just for starters.
 * Edgar Allan Poe: The Fall of the House of Usher
 * Some of Roald Dahl's stories, particularly The Landlady where early on you can tell there's something not right about that woman and her "Bed and Breakfast".

Video Games

 * Bio Shock
 * Peaceful Rest Valley from Earthbound.
 * Fallout 3: Vault 112.
 * Okage: Shadow King - The Highland Village. Everyone there talks in a distant, dreamy tone. Turns out
 * Paper Mario the Thousand Year Door: The Glitz Pit. About halfway through you'll be able to smell a conspiracy brewing.
 * In Pokemon XD Gale Of Darkness, your return to peaceful Phenac Town from the first game is deliberately designed to invoke this. New players won't see what's wrong, but people who've played Pokémon Colosseum will take notice that all of the NPCs are acting contrary to their personalities in the previous game, and the roaming Pokemon are also all wrong (for example, the jogger lapping the fountain has a Duskull following him instead of a Castform). It's unsettling, but at the same time one has to wonder if the programmers just plain Did Not Do the Research about how things were in the first game. And then you find out that  After you've solved that problem, Phenac returns to exactly how you remember it from Colosseum. Well played, Genius Sonority.
 * The Silent Hill series. When a character first enters the town, they notice that no one is around and even before they find their first monster, they know there's something wrong there.
 * Super Mario RPG: Legend of the Seven Stars - The Seaside Town. By talking to the villagers you'll eventually realize that something is wrong here.
 * All of Termina from [TheLegendOfZelda:Majora'sMask\].