The X-Filesis a seminal ’90s sci-fi show that popularized UFOs, government conspiracies, and attractive FBI agents.

This list will rank the most chilling and nightmarish monsters the series ever unleashed.

Hoffman does such a phenomenal job of really selling her torment to the audience.

10-Most-Terrifying-Monsters-in-‘The-X-Files,'-Ranked

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The couple investigates the backyard of the home to find the girl’s father has mysteriously died from exsanguination.

What makes the Eves so terrifying is their unique blend of superficial innocence and cold malevolence.

The two struggle to find a way out of the forest as they fight a ubiquitous enemy.

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Due to their size and volume, the mites are impossible to manage or fend off.

Leonard Betts (Paul McCrane) is not terrifying in that he’s exceptionally violent or malevolent.

In fact, up until the midpoint of the episode, he’s a pretty sympathetic character.

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That’s until he murders his ex-coworker after discovering he faked his death.

This maneatscancer to survive.

It’s his lifeblood.

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He’s a walking tumor.

But when their joke manifests a bunch of unexpected spooky stuff, the kids decide to split.

InThe X-Files’ scariest episode, Mrs. Phyliss Paddock is one cold-blooded player.

Jenny-Lynn Hutcheson as Polly Turner holds her doll in ‘The X-Files’ episode “Chinga."

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On the surface, she’s just an unassuming, mild-mannered, incredibly polite run-of-the-mill substitute teacher.

But beneath this carefully constructed veneer is one of the darkest monsters Mulder and Scully have ever faced.

Mulder develops a psychological profile of the perp and deduces that their fetish will escalate into murder.

Erika and Sabrina Krievins as Eve clones stand together wearing matching creepy red jackets in episode Eve from The X-Files

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Donnie is ultimately apprehended after nearly doing the same to Scully.

Not all monsters are creatures or paranormal beings.

Some of the most terrifying monsters are people.

X-Files Season 3 “2Shy”

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Donnie Pfaster is a perfect example of this.

This is a character that just oozes with creepiness.

“Home” remains the only episode of TheX-Fileswith a TV-MA rating, and for good reason too.

Closeup of the green Darkness Falls Mites in the X-Files.

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It’s often cited as being one of, if not themost horrifying episode ofThe X-Files.

In between kills, Tooms hibernates in a nest made of (you guessed) his own bile.

Tooms is the quintessentialX-Filesmonster.

A man made of cancer cells can make another version of himself in “Leonard Betts,” the post-Super Bowl episode of The X-Files.

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What’s even scarier about Tooms is his longevity.

It’s not entirely clear what his lifespan is, he might even be immortal.

NEXT:The Most Underrated Episodes of ‘The X-Files,’ Ranked

Mrs. Paddock (Susan Blommaert) smiling creepily in the “Die Hand Die Verletzt” episode of The X-Files.

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Donnie Pfaster sits in class during X-Files.

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The Peacock Family in the X-Files epsiode “Home” at nighttime.

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The Fluke Man submerged in water from the episode The-Host in The X-Files

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Eugene Victor Tooms in “Squeeze” X-Files.

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