They Live!/Nightmare Fuel

While not quite as scary as Carpenter's other movies he was famous for at the time, They Live! has some scary moments.
 * For starters, the world through the sunglasses  It's completely monochrome and dull. With subliminal messages on everything from billboards, to magazines, to grocery products and even the cash in your hand. All of which meant to influence the human race into mass consumerism. On top of which there is various bizarre technology all over places.  Such as a small satellite on top of a stoplight and a small UFO.  The props look like something out of a 1950s Sci-Fi movie, making it look more uncanny.  As if things can't get any worse, most of the population that live and work every day, are not even human.
 * The aliens themselves deserve their own category. For starters, they look like rotting zombie versions of humans.  This was intentional to show that they weren't different than us. Second, they are responsible for placing subliminal messages all over L.A. as well as spying on the human race by taking various jobs from business men to local police. Showing that they could be anywhere. If not, then their tech watches you and pinpoints their location.  If you managed to see what they really look like they break character and using a wrist mounted radio, communicate with their leaders, giving them your physical description.  All while staring at you and approaching you slowly. Presumably to better observe and report or subdue you when you least suspect it.  Should you try to stop them, they use a button causing them to teleport away. What's even scarier is that even if you manage to fight back and kill a few of them, it's in their favor. Since they have control of almost everything, including the media, they simply write you off as a wanted terrorist. Turning the city full of humans who can't see you or are working with them against you.
 * The glasses themselves can be Nightmare Fuel. While they are an essential tool, you can't wear them for too long. Nada describes the sensation while wearing them to be like a drug. He also describes to Frank that it also feels like a knife going through your skull.
 * Before the reveal of the aliens we are treated to a nasty scene where a swat team with bulldozers comes to mow down the shanty town. While it later turns out to be the aliens, finding and killing resistance members it doesn't make it less scary.  As it seems they don't know nor care that not all the residents including the newly arrived Nada are resistance members. So they beat, run over, arrest and even kill any that happen to be there. All while tearing down what little shelter they had.  Directly mirroring a violent oppressive police raid.  Nada and a teenage boy he was protecting, barely make it to a hiding spot when a cop car arrives.