There's an unspoken agreement between moviegoers and filmmakers who make safe, mainstream fare: If the former gives the latter's work a look, the latter won't do anything to disrupt the viewers' emotions beyond the norm. There may be some laughs, some jolts, and possibly a tear or two, but nothing that will leave any permanent scars.

Then there are those directors who don't care about that agreement. They want to leave marks.

It's those moments in a movie where people either cover their eyes, peek through open fingers to catch a cautious glimpse, or stare at the screen in disbelief, as if a freight train is pushing toward them and they're frozen in fear. It can be a scene marked by such intense violence that it's nauseating, a conversation so uncomfortable you can't handle the second-hand embarrassment, or some other heinous exhibitions of mankind's darkest impulses.

Whatever the case, they don't get much more aggressive than what's seen in the 50 most hard-to-watch scenes in movie history. Consider this the all-encompassing cousin of last month's collection of traumatic dog death scenes.

BEWARE OF SPOILERS. (Also possibly NSFW/L)

Movie: Antichrist (2009)
Director: Lars von Trier
Stars: Willem Dafoe, Charlotte Gainsbourg

Lars von Trier has publicly stated that he made 2009's Antichrist in a state of deep personal depression—hence why he goes out of his way to convey extreme discomfort and a downbeat mood throughout a film about a husband and wife mourning the accidental death of their infant son. Willingly viewing Antichrist—which we highly recommend you do—is an artsy way of bashing your nerves into mush, without the physical exertion.

During Antichrist's darkest section, "He" (Willem Dafoe) and "She" (Charlotte Gainsbourg) hurt themselves and each other, but She takes the prize for the film's most unwatchable act of self-abuse. With a pair of rusty scissors in hand, She removes her clitoris during an intense round of masturbation.

Movie:Benny's Video (1992)
Director: Michael Haneke
Stars: Arno Frisch, Angela Winkler, Ulrich Mühe

Part of Michael Haneke's project is to make cinematic violence grueling. Benny's Video accomplishes this through duration.

In the film's violent centerpiece, a young boy shoots his friend with a bolt pistol. She falls to the ground. She is not dead, and begins to crawl. Haneke shoots with the camera in a fixed position, with no music. The girl crawls out of the frame, but the camera doesn't pan to follow. Her last moments, then, are conveyed totally through the terrible sounds she makes while dying.

As is the case in many of the most traumatic film experiences, what you don't see is most powerful.

Movie:Inside (2007)
Director: Alexandre Bustillo and Julien Maury
Stars:Béatrice Dalle, Alysson Paradis, Nathalie Roussel

It's a moment so gruesome, so get-the-fuck-out-of-here, that there's not a single still image available online. Our guess: No one wanted to stomach the scene again to freeze-frame a snapshot. We can't blame them-proving that writers/directors Julien Maury and Alexandre Bustillo are fearless and crazy bastards, the deservedly cult-beloved French knockout Inside's climax is the culmination of 70 minutes' worth of "They're not going to go there" speculation. And then they do.

The film's premise is rather straightforward: An enigmatic and psychotic woman, dressed in all black, breaks into a grieving pregnant lady's home on Christmas Eve night to steal the unborn baby from her stomach. And she's armed with scissors for the majority of the movie's running time. And she hacks her way through the homeowner's mother, boss, three police officers, and one arrestee. But then, she's just left with poor Sarah (Alysson Paradis), though she's not going to actually cut Sarah's belly open, right?

Viewers' jaws, already smacking the floor from Inside's previous oh-shit moments of gore, uncontrollably slink even lower once the intruder starts a-snipping; cutting Sarah's stomach open like a pumpkin, the psycho chick pulls the fetus out of the now-dead Sarah, and Maury and Bustillo show the whole thing, steady cam and all. Just one of the many reasons why Inside is arguably the best horror movie of the last 10 years.

Movie:Salò, or the 120 Days of Sodom, (1975)
Director: Pier Paolo Pasolini
Stars:Paolo Bonacelli, Giorgio Cataldi, Umberto Paolo Quintavalle

You've read about Salo's nauseating "shit eating" scene already—now it's time for Pier Paolo Pasolini's main event of unapologetic sadism.

As if the captive teenagers haven't endured enough by the end of Pasolini's film (e.g., fecal dinner, sodomy, and other forms of extreme humiliation), the older Italian fascists decide to finally and unmercifully end the remaining kids' lives in a grand finale montage that will test the endurance of even the most thick-skinned viewers. Don't think just because you lasted through both The Human Centipede movies that you're too tough for Salo's climax—you really aren't prepared.

As the monstrous libertines watch with the at-ease pleasure of golf fans watching an 18-hole competition, the teenagers are offed slowly, painfully, and altogether horrifically. One gets his tongue cut out; another, her eyes. Others get scalped. All suffer tremendously. Anyone who's brave enough to keep watching loses his or her appetite for days.

Movie:Irréversible (2002)
Director: Gaspar Noé
Stars: Monica Bellucci, Vincent Cassel, Albert Dupontel

Told backwards, extreme French auteur Gaspar Noé's Irréversible depicts the aftermath of the most brutal rape scene in all of cinema. Clocking in at nearly 11 minutes long, the unbearably savage sequence is the film's cruel centerpiece. Shot in one unbroken take, the crime is committed in an underground walkway lit red, like everything is occurring behind a wall of blood. Monica Bellucci, who plays the victim, is something like a performance artist for her work here.

Is it worth it? That's up the viewer.