The plot/trope where some crime so violent or egregious has happened that some alien/monster is automatically suspected to be behind it, only for our human protagonists to investigate, and in the end find out the culprits were actually humans has been used in a number of shows, e.g:

  • Torchwood "Countrycide" (2006)
  • Supernatural "The Benders" (2006)
  • The X-Files "Home" (1996)

And probably many more.

What was the first work to feature this plot?

I'm looking for examples of something like the intersection of these two tropes: Human All Along (though perceived to be non-human for their violent actions, not their appearance, which is unknown) and Humans Are The Real Monsters

While interesting, examples where it turns out our protagonists (that we thought were human) are aliens, and the antagonists (that we thought were alien) were actually the humans, are not what I'm looking for!

e.g. Sentry, The Twilight Zone "The Invaders"

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    The suspected "monsters" are not necessarily space aliens, right? People are suspecting the mischief is done by ghosts or witches or devils, but the villains turn out to be mortal human beings?
    – user14111
    Commented May 2, 2019 at 11:15
  • If the monsters are not real, then the story with that plot is not necessarily sci-fi, and therefore not necessarily on topic here?
    – user14111
    Commented May 2, 2019 at 11:19
  • @user1411 yep, exactly - they can be perceived to be any sort of non-human 'monster'. I suppose it may not be necessarily, but all examples I've encountered have been episodes within explicitly sci-fi/fantasy series, and I imagine the story would be 'framed' in a sci-fi way up until the big reveal.
    – Kitsune
    Commented May 2, 2019 at 11:32
  • So you're talking about things like Monsters Inc. and Smallfoot?
    – Aaron
    Commented May 2, 2019 at 22:27
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    Note to readers: the title of this question was edited from "the humans were the monsters all along" to "the monsters were human all along" after several answers had already been posted, and the question text has been significantly changed / clarified as well. Some of the highly upvoted answers below may no longer fit the new wording. Commented May 4, 2019 at 0:40

8 Answers 8


The Legend of Sleepy Hollow (1820), in which Ichabod is frightened by a headless horseman, is a good candidate.

From Wikipedia:

Although the true nature of both the Headless Horseman and Ichabod's disappearance that night are left open to interpretation, the story implies that the ghost was really Brom (an agile stunt rider) in disguise, and suggests that Crane was knocked off his horse and immediately fled Sleepy Hollow, never to return there again.


I Am Legend (1954), by Richard Matheson.

At the end of the novel:

Neville discovers that the new vampires are terrified of him - he is a boogey-man to them, as he has been murdering their kind in their sleep.

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    A new terror born in death, a new superstition entering the unassailable fortress of forever. I am legend.
    – Jenayah
    Commented May 2, 2019 at 13:06
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    @Jenayah If only they'd had the guts to use that in the Will Smith travesty.
    – Graham
    Commented May 3, 2019 at 1:18
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    @Graham I know right... Not necessarily a bad movie, but the ending (even the alternative one) was disappointing :(
    – Jenayah
    Commented May 3, 2019 at 5:18
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    This is missing the "Human All Along" half of the requirement. There's never any doubt that Neville is human.
    – OrangeDog
    Commented May 3, 2019 at 11:03
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    This totally isn't an answer to the question... Commented May 3, 2019 at 15:25

This is the woman who lives in the house … a woman about to face terror, which is even now coming at her from - The Twilight Zone.

The Invaders - The Twilight Zone S02E15 (1961)

A woman hears noises and finds a UFO lands on her roof. Small aliens (looking about 6" tall) come into her house and start attacking her. She beats one and throws it into the fire. The other aliens tries to get away and radios a warning to stay away from the planet.

The camera pans to the markings on the side of the ship, which reads U.S. Air Force Space Probe No. 1. The invaders were not tiny, but were human astronauts from Earth; the woman in the small farmhouse belongs to a race of giant humanoids native to another planet.

Wikipedia - The Invaders - The Twilight Zone S02E15

The Invaders were actually astronauts from Earth (doo doo, DOO doo). The lady actually never speaks throughout the episode. Only at the end of the show is the voice warning to stay away and the showing of the U.S. markings on the space craft.

This is not as old as other answers but seems more in the spirit of Monsters Were Human All Along.

There's a short version on YouTube.

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    "examples where it turns out our protagonists (that we thought were human) are aliens, and the antagonists (that we thought were alien) were actually the humans, are not what I'm looking for!"
    – OrangeDog
    Commented May 3, 2019 at 16:40
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    Isn't there one of those episodes where there's a woman who is treated like an alien at a hospital, but turns out to be human and the surgeons are aliens? Commented May 4, 2019 at 20:30
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    @RedwolfPrograms - that's probably Eye of the Beholder( en.wikipedia.org/wiki/… ) you're thinking of, but it's just that the woman is good looking and everyone else is normally deformed by our standards. I think they were they same people. Commented May 6, 2019 at 15:33

I do not know which story was the first, but I do know of a story decades earlier than the examples in the question that made a big impression on me, a short story by Lord Dunsany.

The story is "Mgamu" published in The Fourth Book of Jorkens (1948). A monster called the sivver-verri is feared by all the tribes in Kenya, and known only by the carnage it leaves behind in huts that it enters. It leaves no survivors as witnesses. No man, woman, or child has ever seen the sivver-verri and lived. "Mgamu" tells the story of the one person who has seen the sivver-verri and lived.

Considering the subject of the question this answers, it may be easy to guess which species the sivver-verri is a member of, but I don't like to give away surprise endings.

And the trope Humans are the Real Monsters should have examples from before 1954 and does have a few including Gulliver's Travels (1726) with the Yahoos, & H.G. Wells's The Island of Doctor Moreau (1896), if they fit the original question closely enough.

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    And how does that story fit the theme? You can put it under spoiler tags.
    – FuzzyBoots
    Commented May 3, 2019 at 21:24

Scooby-Doo (1969) is a good contender.

Most episodes follow exactly the plot you describe:

  • Some crime or shenanigans is afoot (though as a kid's cartoon there isn't egregious violence)
  • Some monster is assumed to be behind it
  • Our human (and canine) protagonists investigate
  • In the end we find out the culprits were actually humans

Whether it passes the "through actions, not appearance" test is debatable. I'm not going to check through every episode, but there are probably ones where it's already assumed to be a monster before the inevitable man-sized costume.

  • The Three Investigators books (1964 - 1987) are similar where people try to scare others away by pretending to be monsters. Commented May 3, 2019 at 22:40
  • That's what lept to mind for me too! I just didn't realise it as was old enough to be a contender for "first"!! Commented May 4, 2019 at 1:57
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    There are episodes with a different plot? Commented May 5, 2019 at 7:09

How about Mary Shelly's Frankenstein. First published in 1818. In the end, who is really the monster?

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    For those who haven’t read it could you edit this to explain better how it matches?
    – TheLethalCarrot
    Commented May 2, 2019 at 19:51
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    I don't think that's an answer to the question asked. While Frankenstein's monster is in part a victim, the humans don't really realise they are the monsters, or that the creature sees them as such (which he doesn't, I think).
    – Jenayah
    Commented May 2, 2019 at 20:10
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    @Jenayah I see where you're coming from, but at various points, Frankenstein himself admits that he finds his own actions monstrous, so it seems like it would stand. Frankenstein's monster initially wishes to make peace will his progenitor, but also eventually comes to hold this opinion, as he pursues his Frankenstein to the latter's death.
    – SomeGuy
    Commented May 2, 2019 at 20:31
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    @Konrad Rudolph Victor Frankenstein creates a child and then abandons that child to its fate, violating his legal and ethical parental responsibility to that child. Thus Frankenstein has often been criticized as being monstrous not for creating the creature but for deserting and abandoning it, and perhaps that was Mary Shelley's intention. Commented May 3, 2019 at 17:31

Mary Shelly's Frankenstein is good, but HG Wells' 1896 The Island of Dr Moreau nails it.

From Wikipedia:

The text of the novel is the narration of Edward Prendick, a shipwrecked man rescued by a passing boat who is left on the island home of Doctor Moreau, a mad scientist who creates human-like hybrid beings from animals via vivisection. The novel deals with a number of philosophical themes, including pain and cruelty, moral responsibility, human identity, and human interference with nature. Wells described it as "an exercise in youthful blasphemy."


Upon his return to England, Prendick is no longer comfortable in the presence of humans, all of whom seem to him to be about to revert to an animal state. He leaves London and lives in near-solitude in the countryside, devoting himself to chemistry as well as astronomy in the studies of which he finds some peace.

Dr. Moreau's end comes when he dies at the hands... paws... of one of the monsters he created when she tried to escape from the pain he was causing her.


Dr No (1962)

The first James Bond movie villain, Dr. No, has a typical Supervillain Lair (Warning: TV Tropes) in Crab Key guarded by a dragon. Locals residents stay away from the island because of the dragon. Anyone who has gone there hasn't returned.

When Bond goes there to investigate Dr. No, he discovers that the dragon is actually a tank with a flamethrower. Dr. No's henchman use it to keep the secret lair from being discovered.

After nightfall, they are attacked by the "dragon" of Crab Key, which is in reality a flamethrower-equipped tank.

I think this fits the requirements, though it's a minor plot point in the movie.

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