No Face Under the Mask

When a character always wears a mask, one will wonder what his face really looks like. Sometimes it turns out that he doesn't have a face. Instead of some kind of mundane climax or anticlimax, we get thrown straight into Nightmare Fuel territory: Instead of a face, the character has some kind of blank slate, rotten mess, arcane forcefield or other completely inhuman thing that does not qualify as being a face.

Also happens when someone mistake a suit of Animated Armor for a person.

Not exactly a Sub-Trope of The Faceless or The Blank, since those tropes are character types and this trope is a situation where a character transitions to the second trope from one specific subtype of the first trope. It's a kind of The Reveal as well as a kind of The Un-Reveal. As such, expect unmarked spoilers. Compare Not a Mask, where what you'd see if you took the "mask" off would probably still be pretty bad.

Anime and Manga

 * In the infamous  of Neon Genesis Evangelion, the hooded demons that  meets are like this.
 * In the manga and anime of Fullmetal Alchemist, Alphonse Elric appears to be a large man wearing a medieval suit of plate armor... unless his faceplate is lifted or his helmet is knocked off, revealing empty space. (Technically it's his soul, as it was bound to the armor when his body was consumed by a failed transmutation spell, but souls are invisible).
 * In Fate/stay night, True Assassin wears a white mask to conceal the fact that he doesn't have a face.
 * Celty from Durarara!! does this with a motorcycle helmet.

Comic Books

 * In the first albums of Lucifer, Mazikeen chose to have a half-face and to wear a mask over the faceless half. Mortals assume she wear it for Rule of Cool or because of some mundane injury. The Reveal freaks out at least one human enough to make a really bad choice.
 * One JLA story had some Applied Phlebotinum separate all the heroes and their secret identities into separate people, and the separated Batman had nothing under his cowl.
 * Justice Society of America villain Johnny Sorrow is an intangible specter while wearing his mask. When he removes it, he becomes solid and reveals an other-dimensional visage so incomprehensibly hideous that all but the most powerful (or blind) of living things will instantly die at the sight of it.
 * This happened in Legion of Super-Heroes when Sensor Girl joined and Ultra Boy used his vision powers to see under her mask.
 * Sort of happened during Batman's first encounter with Anarky. Batman took Anarky's mask off, only to see a flat white plastic surface underneath.

Film

 * Dumb Donald was revealed to literally have no face once he removed his hat in the Live Action Adaptation of Fat Albert.
 * In the climax of the original 1958 version of The Fly, Andre Delambre's mask is removed to reveal the human-sized head of a housefly where his normal head should be.

Literature
"Corum stared at a youthful face which writhed as if composed of a million white worms. Dead, red eyes peered from the face and all the horrors Corum had ever witnessed could not compare with the simple, tragic horror of that visage. He screamed and his scream blended with that of Prince Gaynor the Damned as the flesh of the face began to putrefy and change into a score of foul colours which gave off a more pungent stench than anything which had issued from the Chaos Pack itself."
 * In The Doomfarers of Coramonde, the general of the evil wizard's army is wearing a golden mask. Turns out he is blank under the mask: No eyes, no nose, no mouth, no nothing. The wizard must have either created him or mutilated him horribly.
 * Michael Moorcock's The Queen of the Swords. Corum uses the Hand of Kwyll to open the visor of Prince Gaynor the Damned.

"Camilla: You, sir, should unmask. Stranger: Indeed? Cassilda: Indeed, it's time. We all have laid aside disguise but you. Stranger: I wear no mask. Camilla: (Terrified, aside to Cassilda) No mask? No mask!"
 * When the prince unmasks the stranger at his costume party in Edgar Allan Poe's "The Masque of Red Death", the costume is completely empty.
 * Robert Chambers' The King in Yellow owed an obvious debt of inspiration to Poe, though when it comes to the Stranger at its masked ball (who is probably some kind of Humanoid Abomination) the 'mask' in question may be not so much an example as an inversion:


 * In The Lord of the Rings, the Lord of the Nazgul (the Witch-King) wears a mask-cum-helm to the Battle of the Pelennor Fields, despite having no corporeal head beneath it. In the film version he is seen placing it atop his robe's empty shoulders, in effect defining his head. Otherwise, all the Nazgul wear concealing hoods, which have the same function -- in fact, their robes as a whole define the shape of entirely invisible bodies. Of course, with the benefit of Ring-O-Vision, Frodo gets to see 'through' to the ethereal remains of their faces.
 * In Fritz Leiber's Fafhrd and The Gray Mouser stories, Sheelba of the Eyeless Face wears a mask to conceal the fact that he has no eyes in his face -- if memory serves, there's just a flat patch of skin where eye sockets ought to be. This doesn't seem to cause him any difficulty with vision, but then, he is a mighty wizard.
 * One of the most famous examples is The Phantom of the Opera, who's described in the book as being hideous-looking and skull-faced underneath his mask. This has not held true of all the film adaptations, however, especially the most recent one where Gerald Butler appears to have just a mild skin rash underneath his half-mask.

Live Action TV

 * Not only does Omega from Doctor Who lack a face under his mask, but he doesn't even have a body. His willpower was the only thing that kept his existence.
 * The Headless Monks are another example, having no heads beneath their hoods.
 * At the season six climax of Stargate SG-1, master villain Anubis sheds his mask to the ascended Daniel Jackson, who reacts with considerable surprise. Not until partway through the second season would we find out what lies beneath his mask and cloak: a black, cloudlike energy form, the physical manifestation of the "half-ascended" Anubis.
 * Stark of Farscape has two-thirds of a normal humanoid face, while the other third is a shimmering golden energy mass with telepathic properties, normally hidden beneath a leather mask.

Video Games

 * Bobbin Threadbare and the rest of the Weavers from Loom.
 * The Shy Guy Ghosts in Luigi's Mansion.
 * One possible answer to the question of what's under Darth Nihilus' mask in Knights of the Old Republic 2.

Web Comics

 * In Exiern, we have a woman who has a human body but no face or physical brain. Instead, her mask hides a swirl of bluish energy that she can use in combat. At first, the kids who run into her and knock her mask off don't realize this.
 * Parodied in Dark Legacy Comics. In one strip, two characters are busy unmasking "liars", thus ruining everyone's Halloween costumes. In the end, they "unmask" a pandaren by tearing of his real face. Since he doesn't have any face left under that "mask", well, ewwww....

Web Original

 * Ruby Quest has Ace, who wears a metal mask. Beneath it, his "face" is a writhing mass of tentacles or possibly worms.

Western Animation

 * Hexadecimal of Re Boot.
 * Played with in Bionicle; the Toa Inika's faces glow brightly when they remove their Kanohi. Setwise, their faces are just blanks.
 * An episode of He-Man and the Masters of the Universe featured such a villain.
 * Invoked in the very first Strong Bad Email from Homestar Runner where Strong Bad actually mentions that taking off his mask and boxing gloves is the same thing as taking off someone's face and hands. Another Email was actually about him actually taking off his mask, but when he does so, he is completely covered up by the back of the new chair he bought from Bubs in the same Email. Maybe his mask really is his face after all.
 * On one episode of Jackie Chan Adventures, a villain created magic clones of the heroes, including El Toro Fuerte. Later, when the heroes accidentally removed his clone's mask, he was like this (however, this was more of a spell glitch than an intended/expected side effect). The others turned out.