The horror film is like pornography in the sense that, while it’s really hard to boil it down to a precise definition, like Supreme Court Justice Potter Stewart famously remarked, “I know it when I see it.”

Are horror films explicitly supernatural in nature? Do they require intense violence and gore to meet official genre classification? Can they exploit abstract and metaphorical fears instead of direct, physical ones, or do they explicitly have to be about people running away from something that wants them very, very dead? Film historians and forum nerds have long grappled with these unanswerable issues, but to the layman, a film needs to be just one thing to earn the “horror” label – all it has to do is scare the living hell out of you.

Some films are very obviously horror films using that specific criteria. The Exorcist, Halloween, Poltergeist, Scream, Silence of the Lambs, Spice World … all clear-cut, by-the-book, no doubts about ‘em horror movies, through and through. But what about the movies that aren’t necessarily designed to scare the crap out of you from start-to-finish, but nonetheless port about a very palpable air of unease, discomfort, dread and yes, even good old fashioned terror?

Today, I would like to pay tribute to ten of the most terrifying films ever made that, for all intents and purposes, weren’t explicitly designed to scare you senseless. World War II tearjerkers, weirdo surrealistic arthouse ventures – heck, even a few bona fide family classics ended up making the cut. While none of these movies may technically be horror films, there’s no doubt they’ll give you the heebie-jeebies, all the same…

10. Willy Wonka and the Chocolate Factory (1971)

Considered an all-time family masterpiece by anyone who isn’t stupid, Willy Wonka also holds the proud distinction of containing one of the most insanely horrifying scenes in any movie ever. As soon as Gene Wilder loads the kids onto that damned ferry, Willy Wonka ceases to be a whimsical children’s yarn and instead turns into a methamphetamine addict’s darkest nightmares made flesh. One minute, we’re licking flavored wallpaper and watching fat German kids almost drown in rivers of Yoo-hoo, then all of a sudden, the dude from Blazing Saddles starts rapping about “grisly reapers mowing” while stock footage of slugs crawling over dead bodies and chickens being beheaded plays in the background. From there on out, the movie is never the same … and neither is anyone who gets blindsided by the ultimate unnerving “big-lipped alligator” moment in cinema history. 

9. Gummo (1997)

https://www.youtube.com/watch?v=4u7UG6n5100

I’m not entirely sure what genre – if any – you can place Harmony Korine’s 1997 magnum opus’ in. Alas, the surreal reverse slice of life narrative is nonetheless one of the most deeply troubling films you’ll ever encounter – I mean, for crying aloud, the central plot of the movie revolves around competing glue-sniffing juvenile delinquents killing cats to sell to the local butcher shop. Even without the subplots about unplugging senior citizens on respirators for fun, the skinheads bare knuckle boxing for no reason in their kitchen and a pimp trying to pawn off his Down Syndrome-afflicted sister, this one is still all shades of unsettling.

8. Eraserhead (1977)

And here’s yet another cult classic that utterly defies genre relegation. Since the main character is never really placed in any sort of direct physical harm, it’s a bit of a stretch to call Eraserhead a “straight” horror film. But then again, with subplots involving the murder of a mutant chicken-nugget fetus, a chipmunk cheeked radiator fairy stomping spermy bugs to death during dance routines and a dream sequence in which the primary protagonist is decapitated and has his skull manufactured into a No. 2 pencil, I nonetheless struggle to find an appropriate synonym.

7. Suicide (2004)

https://www.youtube.com/watch?v=gxeWTiNk6Sg

Found footage movies are a dime a dozen nowadays, but Suicide definitely stands out from the pack because of its distressingly real pseudo-documentary approach. An obscure German flick from the early 2000s, Suicide revolves around a team of website operators who drive around the Deutschland countryside, helping people end their own lives just as long as they agree to let them record it and upload it to their servers. While you really can’t call the movie a pure horror film, I assure you the death scenes in this film are beyond-haunting – the death wails of the guy who injects air into his veins has to be one of the single most horrific sounds I’ve ever heard, at the movies or anywhere else, for that matter.

6. Men Behind The Sun (1988)

A legendary Hong Kong “exploitation” film, Men Behind The Sun is a wartime drama that examines the very, VERY unsettling things that went down in General Ishi’s infamous Unit 731 in Manchuria (and if you haven’t heard about it … well, get ready to heave buckets.) Based on real life atrocities committed during World War II, Men Behind The Sun contains some of the most horrific scenes you will see in any movie, regardless of the genre. Up-close child autopsies, people having their frozen skin peeled down to their bones, REAL cats being chewed to death by mice (some of whom were literally set on fire), and even a real knee-slapper involving a dude being depressurized to death are among the terrible, terrifying sights that will assail your senses … and it’s made immeasurably worse because it’s all based on documented historical facts.

5. Combat Shock (1986)

https://www.youtube.com/watch?v=ZTH6ntY9IaE

Troma is notorious for schlocky, no budget shockers like The Toxic Avenger and Class of Nuke ‘Em High, but this is no tongue-in-cheek self-parody. Rather, Combat Shock is an eerily prescient psychological drama about an unemployed Vietnam veteran living in Long Island, haunted by PTSD and whose infant child is horrifically disfigured by the chemical aftereffects of Agent Orange. Hours away from being evicted, the main character slowly sinks into madness, culminating with what very well be the most depressing ending you’ll ever see in a motion picture. Yes, it has some admittedly corny elements, but the total atmosphere of this one is utterly unforgettable – and with joblessness, lackluster veteran care and substance abuse still eating away at the roots of American society, it’s also a film that hits way closer to home than you’d ever want it to.

4. Salo, or the 120 Days of Sodom (1975)

Italian virtuoso Pier Paolo Pasolini’s final film – 40 years later – remains one of the most controversial movies ever made. Set during the waning days of Fascist rule in Mussolini’s Italy, the film itself is a bit of a modernization of Marquis de Sade’s notorious magnum opus – you can conduct the totally NSFW research on your own time. Eschewing the visceral guts and gore of most standard issue genre films, Salo instead assails you with an entirely different type of “body horror” – mainly, via some truly disturbed deviant acts that I am verboten by this publication from even describing (in case you are curious, poop does factor prominently as a plot device, though.) This is a movie that just excels at making you feel distressed and unnerved, even when (seemingly) absolutely nothing out of the norm is transpiring on screen … all the way up to its’ extremely shocking Grand Guignol ending I wouldn’t dare dream of spoiling.

3. Schindler’s List (1993)

When it comes to historical horrors, the Holocaust is generally considered as bad as it gets. While the lamentable, regrettable and unfathomably tragic episode of the 20th century has been the focus of many, many films, no dramatization of the Holocaust has been as impactful – and stomach-souring – as Steven Spielberg’s 1993 Academy Award winner. Even in black and white, the images of bodies being burned, children having to hide in latrines and people being gunned down in the middle of the street remain among the most difficult scenes to watch in any film. Especially gut-wrenching and heart-palpitating is the sequence in which recent Auschwitz transports are slowly, painfully processed through the slaughterhouse … with a momentary reprieve in the showers of death only serving to make the butchery ahead all the more devastating.

2. Johnny Got His Gun (1971)

One part anti-war screed, one part historical drama and one part surreal head trip, it’s next to impossible to neatly fit Johnny Got His Gun into any one genre. Directed by Dalton Trumbo (the same man who wrote the 1939 book the film is based upon), Johnny Got His Gun revolves around a World War I soldier who has his face blown off and all of his limbs severed in battle. The entirety of the movie is him, lying in a hospital bed, recalling his pre-WWI life and experiencing all sorts of indescribable, Dali-esque nightmares – all the while mustering all his might to convince the night nurse to euthanize him. There really isn’t another movie out there quite like this superb 1971 flick … and there aren’t that many as thoroughly disturbing, either.

1. Zero Day (2003)

Simply put, Zero Day is the most terrifying movie I’ve ever seen. A large part of that is because the film lulls you into a false sense of comfort. It makes you like and relate to the main characters, and convinces you they are incapable of doing the very deadly thing they keep promising to carry out. You keep expecting something to happen, some fantastical, dramatic, Hollywood-esque change of heart, with our anti-heroes suddenly embracing their own humanity and worthiness. But – as the case at Columbine, Sandy Hook, Aurora and Virginia Tech – such does not turn out to be the case.

There have been many, many movies about mass shootings over the years, running the gamut from the artsy (Gus Van Sant’s Elephant) to the sleazy (Uwe Boll’s Rampage series), but none of them have had the soul-crushing, heartbreaking, stomach-churning intensity of Zero Day. Fundamentally a “found footage” style flick in the vein of Paranormal Activity and its ilk, the 2003 movie chronicles the exploits of two would-be school shooters, obviously inspired by Eric Harris and Dylan Klebold, as they make preparations for mass murder. Rather than paint the two characters as one-dimensional psychopaths, they come off as real teenagers, two kids who, while slightly confused about themselves and the world they live in, nonetheless put forward uncomfortably sound rationalizations for embarking upon a killing spree to make a “point” about the shallowness and ugliness of modern U.S. society.

None of us have to worry about zombies or vampires or werewolves or becoming demonically possessed or getting chased through the wilderness by some guy with a chainsaw wearing a hockey mask. But each of us – every single day – runs the risk of being mowed down in some senseless mass shooting every time we step foot in the public square. It’s the ultimate post-post-modern horror, and ultimately, no film does as good a job displaying that all-too-real terror as vibrantly, as horrendously and as tangibly as this criminally underappreciated masterpiece from 2003.