The X-Files celebrates its 30th anniversary this year. The iconic series of government conspiracies, aliens, and monsters slipped seamlessly between scary and silly over the course of nine seasons (plus a two season modern revival). 

In honor of the show’s anniversary and this Halloween season, let’s take a look back at Mulder and Scully’s spookiest investigations. Here are the scariest X-Files episodes from each season of the show.

Season 1: Episode 3, “Squeeze”

Eugene Toombs in S1 E03 "Squeeze"

The first two episodes of The X-Files gave us aliens and government conspiracies, but episode 3, “Squeeze,” showed audiences supernatural horror would act as another key pillar of the series. And the “monster-of-the-week” Eugene Toombs remains one of the scariest the show ever created. (And one of only a few to make a repeat appearance in a future episode.) 

It’s not just his supernatural ability to stretch his body and squeeze in anywhere to get you and eat your liver; it’s how creepy he is even when he’s not doing that. Toombs looks sort of slow and sickly, but in a calculated way. No one is going to believe you about him – and then it’s going to be too late. More than that, when the episode culminates in Toombs attacking Scully in her apartment, we realize something important and terrifying: the monsters don’t just stay in case files. Sometimes, they follow you home.

Honorable Mention:

Season 1 of The X-Files wasn’t short on scares, so it’s honestly hard to choose just one honorable mention. But the scene in “Darkness Falls” where Mulder and Scully huddle together in a remote cabin, with just one flickering lightbulb and a failing generator standing between them and an insect swarm promising a horrible death? Well, that’s one that still sticks with me, years later.

Season 2: Episode 13, “Irresistible”

Gillian Anderson as a kidnapped Scully in the X-Files episode "Irresistible"

The X-Files was all about the supernatural, the sci-fi, and the generally unexplained… But once in a while, it wasn’t. “Irresistible” introduces Donnie Pfaster, a stalker, death fetishist, and murder who is evil in a horribly mundane way. 

The thing that makes “Irresistible” so terrifying is that the exact story could appear in a true crime series. Pfaster works in a morgue, carving bits and pieces off of bodies to take home for his own private collection. When a sex worker discovers his collection, he kills her. When he makes threatening advances to a different woman, he’s picked up by police… who ultimately let him go. He stalks Scully, runs her car off the road, and kidnaps her, before Mulder eventually tracks him down. In the end, Pfaster isn’t preternaturally powerful; he’s just deeply upsetting and unsettling because of how very evil a “normal” person can be – and how long he could get away with it. 

Honorable Mention:

Mulder and Scully investigate many a terrifying small town over the course of The X-Files, but the cannibal cult lurking behind a chicken processing plant in “Our Town” is one of the standouts.

Season 3: Episode 14, “Grotesque”

David Duchovny as Mulder in the X-Files episode "Grotesque"

A pretty standard format for a monster-of-the-week X-File is “person gets possessed by [insert this week’s specific scary thing here] and starts killing people.” And true, that’s the basic story here. But “Grotesque” stands out thanks to some impressive cinematography, eerie imagery, and raised personal stakes.

In this episode, Mulder and Scully are called to investigate when a man claims a gargoyle spirit possessed him and caused him to mutilate and kill several people. Mulder soon finds himself drawn further into the case than he could have expected, experiencing his own hallucinations and nightmares plagued by gargoyle creatures. The more he pulls away from Scully and appears to descend into his own madness and obsession, the more tension the episode builds. This one has a good blend of psychological horror and creature scares.

Honorable Mention:

Ok, “Pusher” is much more of a thriller than a horror story, but the tension this episode racks up is top-tier. The story sees Mulder and Scully confront a man who can make anyone do anything, simply by willing it to happen. After several shocking deaths, the episode culminates with Mulder playing mind-controlled Russian Roulette with the killer.

Season 4: Episode 2, “Home”

The Peacock family farmhouse in the infamous X-Files episode "Home"

The first episode to air with a viewer discretion warning, “Home” is undeniably The X-Files at its most f-ed up. While The X-Files was frequently unnerving and occasionally grotesque, it rarely tipped over into truly violent and disturbing. But when Mulder and Scully arrive to investigate the death of a baby and the story still manages to escalate from there, you know you’re in for something uniquely horrifying.

Our FBI Agents find themselves up against the Peacocks, a family of violent recluses deformed from years of inbreeding and fiercely protective of their farmhouse home. It’s an episode where every new revelation proves more horrifying than the last. No one who’s watched “Home” forgets the moment when the family matriarch is finally revealed…even if you wish you could.

Honorable Mention:

The guy kidnapping people and giving them lobotomies to free them from “the howlers” in their head in “Unruhe.” The main clues from the case are the creepy psychic photographs of his victims.

Season 5: Episode 19, “Folie à Deux”

Office cubicle jobs aren’t really scary (minus the sort of existential dread brought on by capitalism). But leave it to The X-Files to make “my boss is a monster” literal and terrifying. 

“Folie à Deux” is great because it works the scares on different fronts: the creature itself, with its sudden appearances and jerky movements and ability to scale walls; the flickering glimpse of its victims in a zombie-like state; the dread and paranoia of figuring out who might be a monster in disguise; and the fear that no one will believe you and help, even if you do figure it out. The X-Files loves its monsters, its conspiracies, and its paranoia, and “Folie à Deux” delivers all three.

Honorable Mention:

Horror icon Stephen King wrote “Chinga” about a cursed doll tormenting Scully when she’s supposed to be on vacation. Need I say more?

Season 6: Episode 21, “Field Trip”

Only The X-Files could make a plotline like “eaten by a giant mushroom” scary. “Field Trip” isn’t scary in the same vein as many other X-Files episodes, full of monsters and aliens and people with dangerous, otherworldly powers.

Instead, “Field Trip” is a great example of a different approach to horror: the kind full of creeping dread and a mistrust of your own senses. Of not knowing the difference between reality and hallucination, or between waking and dreaming. Bog sludge has never been so ominous.

Honorable Mention:

“Tithonus” plays up the fear of impending doom by literally marking those soon to die – a creepy premise that adds even more tension when Scully herself appears marked by Death.

Season 7: Episode 14, “Theef”

X-Files season 7 episode 14 "Theef"

On the whole, season 7 is a lot more goofy than scary. But you can easily get your fix of scares with “Theef.” The story follows a man practicing “hexcraft” (think voodoo, but a bit different) to exact revenge on those he believes responsible for his daughter’s death. This episode brings it all: eerie totems of dark magic, graverobbing, and multiple gruesome deaths. Like, a woman gets cooked alive inside an X-ray machine type gruesome. Talk about nightmare fuel.

Palate Cleanser:

We’ve been in scary mode for a while now, so why not take a moment to embrace the sillier side of The X-Files? If you still want a little spooky element with your laughs, try “X-Cops.” If you want full-on ridiculous, go for “Je Souhaite.”

Season 8: Episode 4, “Roadrunners”

The X-Files fundamentally changed when David Duchovny started distancing himself from the show. (And let’s be honest: by this point, the novelty and intrigue of the mytharc plots had really dried up, too.) But “Roadrunners” did a lot of heavy lifting to recapture that classic, creepy magic of the show’s earlier days. 

The episode returns to the ominous isolation of small-town horror, elevated by the fact that Scully’s investigating this one solo. It hits all the hallmarks: weirdly religious and standoffish townsfolk, sabotaging Scully’s car to trap her in town, and even a gross slug monster parasite moving under people’s skin, Alien-style. Just try and tell me you don’t cringe when Doggett arrives and has to cut one of those slug things right out of Scully’s back.

Honorable Mention:

“Via Negativa” is sort of the Nightmare on Elm Street of The X-Files, with an eerie story about dreams that can kill – or make you kill.

Season 9: Episode 8, “Hellbound”

Oh, season 9. Generally I’m of the opinion that if you don’t have anything nice to say, you should just keep your silence, so I’m going to do just that. This season doesn’t give us much for scares or monster-of-the-week content, but you can get your fix with “Hellbound” well enough.

Agent Reyes takes the lead in this case, which involves people having premonitions of being skinned alive. And then, well… I bet you can guess what happens next. As you can imagine, this episode features plenty of solid gross-out effects, with blood and guts galore.

Season 10: Episode 2, “Founder’s Mutation”

Mulder screaming in pain in the X-Files revival episode "Founder's Mutation"

Full disclosure – I’m not a big fan of this revival season. And with only six total episodes in the season to choose from, our choices for awarding one the horror crown are pretty limited. So, it’s going to “Founder’s Mutation.”

The story starts with an intense suicide – a researcher shoves a letter opener through his ear and into his brain. When Mulder and Scully arrive to investigate, they ultimately uncover a series of experiments being conducted on children with debilitating genetic conditions, some of whom appear to have supernatural powers.

Honorable Mention:

Just watch “Mulder and Scully Meet the Were-Monster” okay? I know it’s way more silly than scary (though there’s a few surprise jump scares), but honestly I think it’s the only episode from this revival season unequivocally worth watching.

Season 11: Episode 8, “Familiar”

Mr. Chuckleteeth looks out from behind a tree in the X-Files revival episode "Familiar"

Have you ever watched a children’s show and thought the too-smiley characters were actually a bit creepy? Well, here comes Mr. Chuckleteeth. “Familiar” sees this kids show character jump from the TV screen into reality, where he starts isolating and killing the kids who love the program.

As Mulder and Scully investigate, they find themselves going up against the otherworldly powers that brought Mr. Chuckleteeth to life, getting embroiled in a series of witchy rituals summoning a demonic entity. It may not be a hugely standout story, but you can’t look at Mr. Chuckleteeth’s grinning face and tell me you’d be happy to see him out and about during your walk through the woods.

Honorable Mention:

Where would horror be without the evil doppelganger/mirror person trope? See it in action in “Plus One.”

What are your scariest episode picks?

Did I miss any of your favorite X-Files scares? (I had a really hard time choosing for some seasons with great horror options!) Let me know in the comments below which episodes scared you the most.

All eleven season of The X-Files are currently streaming on Hulu.