In Dagon, almost everyone in Imboca has one of these.
The title character in Darkman gets this trope after mobsters attack him and destroy his lab, leaving him horrifically burned. He then goes about seeking revenge on the villains for his disfigurement.
In The Devil's Advocate, John Milton (Al Pacino) and all the representatives of his law firm are actually Satan and his half-human bastard children, respectively. Several of them reveal their true faces, which remind one of living corpses or vampiric cats. Milton himself goes One-Winged Angel at the film's fiery climax, showing himself as both an emaciated humanoid with wings and (subliminally) a short, greenish-skinned, grinning troll.
In The Devil's Nightmare one of the guests says "The butler has a face that would give you a nightmare."
The Exorcist gave us two scary faces- namely, the girl herself and the subliminal white face that appears randomly in the movie and in the director's cut- also known as Captain Howdy or Pazuzu.
Private Pyle from Full Metal Jacket wears a truly disturbing one during his final plunge into madness, shouting various drill commands while holding a loaded rifle.
Ghostbusters is mainly considered a comedy, but the below examples could nicely put it in the realm of horror.
Bruce Barton in The Cyclops has half of his face melted off, obliterating his right eye and exposing his teeth partially. His remaining eye glares unblinkingly.
Glenn Manning has a similar deformity in War of the Colossal Beast, except he's missing all of the skin and muscle on one half of his face, exposing parts of his skull. He's kind of a cyclops, too, in that one eye is just an empty socket.
During Godzilla's meltdown at the end of Godzilla vs. Destoroyah, a close-up is given of Godzilla's head as his flesh slowly begins to literally melt off his skull.
Played for laughs in Harry Potter and the Order of the Phoenix, when Uncle Vernon makes a very over-the-top malicious face when he says "Justice!" in the beginning.
In Hellraiser: Inferno, Joseph keeps seeing visions where random people's faces momentarily transform into eyeless Cenobite faces.
The Hug: We see Pandory's realface for the brief moment he's dragging Aiden backstage to eat him.
The Indiana Jones series has its fair share of Nightmare Faces, but the climax of Raiders of the Lost Ark, where the Nazis open the Ark of the Covenant, takes the cake, with four examples of this trope in the span of 50 seconds. First, one of the spirits that come out of the Ark suddenly morphs into a skeletal Angel of Death and howls angrily at the screen. This is followed moments later by the main villains, whose heads shrivel up, melt, and explode, respectively. Some first-time watchers will no doubt wish they'd heeded Indy's warning not to look.
The ending of Invasion of the Body Snatchers (1978) has Donald Sutherland giving an unearthly scream as he points out the one remaining human. Also scary because it's a shocking plot twist.
Many of the protagonist's visions in Jacob's Ladder manifest in this way.
Arthur Fleck, the Joker (2019) version of the archenemy of Batman, give himself one after being freed from a police car after his believers slammed an ambulance into it by sporting a Slasher Smile and smearing his own blood from his mouth and nose onto his cheeks to replace the "lips" of his makeup.
The Man Who Laughs is about a man whose face is carved into a permanent Slasher Smile - although he's actually the movie's romantic hero. A poster for it is said to have inspired Batman villain The Joker.
Mr. Sardonicus's face from the film of the same name froze into a hideous grimace after he opened a grave and saw its inhabitant.
The Mummy (2017) has the faces of Ahmanet's zombie mooks, as well as Nick Morton's face as he uses Set's powers to bring Jenny back to life.
JUST WAKE UP!
Nutcracker Massacre: Whenever the 6-foot tall Nutcracker kills someone, it does so with an angry face that shows off its sharp teeth, as seen here◊.
The 2008 U.S. remake of One Missed Call basically uses one of these as its unofficial mascot: a sinisterly smiling face with screaming mouths for eyes. It's on the DVD case as well, as well as in all promotional material.
Reportedly, there were incidents with viewers fainting in shock at the unmasking scene in the silent film version of The Phantom of the Opera (1925), starring Lon Chaney Sr. who did his own make-up, going as far as to use metal wires to mold his face. To this day, his portrayal of the Phantom remains by far the most faithful to the original novel - and certainly one of the most effective. Its use of this trope is one of the Ur Examples within film.
The main possessed character in Prince of Darkness winds up getting this. At the very end, we have a jump scare where the main character wakes up and sees his love interest, having previously trapped herself in Hell, appears next to him now also with a possessed appearance.
Lothar, The Brute employed by the Nazis in The Rocketeer. What's scariest about his face is that it doesn't look like it could actually move, let alone change expression... but it can. Sadly, based on a real actor with acromegaly, Rondo Hatton.
Angelaat the end ofSleepaway Camp in the most famous scene of the film. Bonus points: not only is it the last shot of the film, but the screen freezes and the end credits scroll over it, so viewers get to have the thing burned into their brain. It's somewhere between horrifying and hilarious.
Son of the Mask has a few of these with the Mask itself, but they're mostly meant to be funny.
Willem Dafoe didn't get a lot of chances to do so in Spider-Man, since the mask covered his face for most of his moments as the Green Goblin. But when he reprised the role in Spider-Man: No Way Home, he loses the mask early on, letting him go all out with terrifying facial expressions of all kinds.
in his short film Bedfellows.
