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10 Most Invasive Alien Monsters

Our latest 31 Days of Horror Lists ranking looks to the stars and finds only monsters.
Horror Lists Invasive Alien Monsters
By  · Published on October 21st, 2021

October is defined in Webster’s Dictionary as “31 days of horror.” Don’t bother looking it up; it’s true. Most people take that to mean highlighting one horror movie a day, but here at FSR, we’ve taken that up a spooky notch or nine by celebrating each day with a top ten list. This article about the best alien monsters is part of our ongoing series 31 Days of Horror Lists.


In space, no one can hear you scream. Pfft. That’s no fun. Earth is where the party’s at, and that’s why the skies rain thick with alien invaders. These nasty extraterrestrials ditch their home planets for ours because we present the tastiest meals for the best price. Do you think a xenomorph on Pluto can find a more delicious snack than the buffet of humans lining outside a GameStop for a PS5 midnight release? No way.

Every morning we wake up and find madmen and serial killers living next door. Our neighbors are terrifying, and that’s why we have to imagine a far more horrible scenario existing somewhere up there in the stars. We can’t be the worst this universe has to offer. There must be a beast deadlier than humanity.

Our Boo Crew, consisting of Chris Coffel, Rob Hunter, Mary Beth McAndrews, Meg ShieldsAnna SwansonJacob Trussell, and myself, was tasked with finding the deadliest alien invaders in cinema — that don’t involve the stars of Alien (or Predator, for that matter). Those beasties have had their time in the sun, so we’re here to shine a light on other intergalactic monstrosities. These monsters come in all shapes and sizes and attack our way of life through various channels. And more often than not, we deserve their vicious, star-born judgment.


10. They Live (1988)

They Live Aliens Horror Lists

Aliens typically conjure up very specific images. For some, it’s big-eyed green beings that beam unsuspecting country folk up to their spinning saucers and poke and prod them with cold metal instruments. For others, it’s slimy, big-toothed creatures with a taste for human flesh. For John Carpenter, aliens look like the everyday people seen in all walks of life. They’re our neighbors, co-workers, celebrities, and politicians. They’re controlling us, forcing us to consume, obey, and ridding us of independent thought. Fortunately for us, we’ve got Roddy Piper, Keith David, cool shades, and not quite enough bubblegum. (Chris Coffel)


9. Under the Skin (2013)

Under The Skin Aliens

While the bulk of the aliens on this list take some kind of monstrous form, the alien visitor here comes packaged in Scarlett Johansson’s body. We first see her examining a dead (comatose?) woman before venturing off into the streets of a Scottish city. She lures horny men back to a rundown house only to leave them quite literally consumed by the “alien” floor. A sequence on a beach where she bashes a man’s head in while a couple drowns and their baby cries is a masterful piece of dread and tension.

Things take a turn, though, when this alien being discovers a curiosity and empathy toward life, both of others and herself, and it marks her downfall. Her “superiors” are in pursuit, in male bodies, of course, furious at the audacity of her free will. She’s felled by a very human monster, one far more evil than she ever was, who leaves her true form exposed to the world — an androgynous, jet-black humanoid form — and screaming while ablaze. Horrifying stuff. (Rob Hunter)


8. Species (1995)

Species Hr Geiger

Species is what happens when you tell H.R. Giger that he could be hornier. Where Ridley Scott took Dan O’Bannon’s gonzo script featuring an alien slasher cutting its way through several grumpy space truckers and elevated it into an unrelentingly scary art piece, Species director Roger Donaldson took Dennis Feldman’s screenplay and dragged it down into the muck of B-movie terror. And Giger was only too happy to supply an alien monster that would’ve made Scott blush. Sil is a collection of genitalia and kitchen cutlery, slippery and sharp, naughty and nice. Your decency asks you to look away, but your wickedness begs you to stare deeply and unblinkingly. Who knows when you’ll see something so hypnotically confusing again? (Brad Gullickson)


7. Killer Klowns from Outer Space (1988)

Killer Klowns From Outer Space

The peak of this film’s quality should be its title, but the Chiodo Brothers refuse to settle for a cheap giggle. Well, they refuse to settle for just one cheap giggle. Killer Klowns from Outer Space is an endless cosmic train of giggles. The center of which is a motley crew of alien monsters in the form of deadly space clowns, designed to perfection, eliciting the most horrendous nightmares for children denied sleep suppressants by their loving and caring parents. The Chiodo Brothers pervert every circus cliché in this film, morphing clown cars and cotton candy and rubber noses into the most twisted and deadly sci-fi instruments. It’s the kind of movie where you’re continuously shouting at the TV, “this is so dumb, this is so dumb,” but as your brain tries to deny its pleasures, your belly is rollicking. You can’t stop laughing. But also you’re a little afraid to go to sleep later. You never want to meet these Klowns in your dreams; you’d prefer Freddy Krueger. (Brad Gullickson)


6. Critters (1986)

Critters Aliens Movies

Don’t you dare call Critters a Gremlins knock-off. Only a jackass would do so — a jackass who has never blindly reached under their couch only to be stabbed by a rusty spring and then pulled back as their violent imagination materialized a grinning Crite hiding in the shadows below. Maybe the Joe Dante film helped get a greenlight for Critters, but this movie is its own unique beast. The Crites, those criminal bastards from space, are a terrifying collection of teeth and fur. Their design is beautifully simple and easy to replicate into an army. They’re not thinking about the past. They’re not worried about their future. They’re only concerned with the now and how much meat they could jab in their gullet. That meat can be a cow, or it can be Billy Zane; they don’t care. They just need their bellies full. (Brad Gullickson)

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Brad Gullickson is a Weekly Columnist for Film School Rejects and Senior Curator for One Perfect Shot. When not rambling about movies here, he's rambling about comics as the co-host of Comic Book Couples Counseling. Hunt him down on Twitter: @MouthDork. (He/Him)