Paranoia is one of the most essential emotions in art. What would pop music, for instance, be like without it? But for real paranoiac pleasures, you have to go to the movies. The lurking shadows, the creepy gazes, and the pulse-pounding music all help create a tense atmosphere. Here are five of the best movies about paranoia, that may or may not have messages directly to you encoded with in them.

"The Treasure of the Sierra Madre"

Paranoia is one of the primary symptoms of the condition known as "gold fever." Whenever there's a pile of gold around, gold fever starts to set in, and people go a little crazy. That's the general idea behind John Huston's movie, which shows Humphrey Bogart going so far into the wormhole of paranoia that he outright tries to murder a man who'd earlier saved his life. It's a true classic, and is the prototypical movie about paranoia.

"Invasion of the Body Snatchers"

All the screen versions of this classic horror story are based on the same basic paranoid idea: What if the people around you aren't who they appear to be? Going further, what if they're actually alien pod-people, sent to replace humanity with emotionless facsimiles? In terms of pure paranoid fear, the 70s version is the best, featuring slightly off-kilter goings-on from the very beginning. They're here! They're here! And they're coming for you, next!

"The Manchurian Candidate"

The plot itself might sound like the ravings of a hopeless paranoiac: The Communists, in league with far-right-wing politicians, have planted a brainwashed military man inside a presidential election and are using fellow brainwashed assassins to make sure he gets into the Oval Office. Sounds crazy, right? But what if it really happened? That's the idea behind "The Manchurian Candidate," featuring star Frank Sinatra doing his best crazy-man impression. Only this time, the crazy man is right!

"The Conversation"

One of the best movies about paranoia ever made, Francis Ford Coppola's sinister 70s thriller stars Gene Hackman as a surveillance expert who comes to believe that he himself is under surveillance, by clients who used his skills to facilitate murder. The paranoia runs as thick as the blood in his nightmares, and people in the audience could be forgiven for checking their phones for surveillance equipment after the movie is over.

"They Live"

John Carpenter's riff on the "Body-Snatchers" conceit has a simple twist: What if the aliens were Republicans? That horrifying thought is spun out into one of the great science-fiction/action/horror films of the 80s, and one that has a thick layer of paranoia all over it. Roddy Piper plays a blue-collar worker who stumbles upon a pair of sunglasses that show him who's human, and who's not. So he does what any decent American would do: Go on a machine gun rampage.