When most people think of The X-Files, they think of aliens. If there was one phenomenon Agents Fox Mulder and Dana Scully were most immersed in over the course of the show’s original nine seasons and two feature films (not to mention the series revival) it was the promise of extraterrestrial life beyond our own planet.

But as often as the show revisited its own grander mythology, it also spent just as much time sending Mulder and Scully to the far corners of America, where they uncovered the weird, wild and sometimes wonderful “Monsters of the Week” that described monster-hunting episodes over the course of the series. Some of the beasts were just misunderstood, but what about the ones that were genuinely creepy? We’ve rounded up a list of some of the scariest X-Files monsters that Mulder and Scully ever went toe-to-toe with.

Eugene Victor Tooms (“Squeeze”, “Tooms”)

Tooms is one of the creepiest X-Files characters ever encountered by our intrepid FBI agents, and he was also one of the first outside the main mythology. Tooms might appear like your garden-variety serial killer, but with a twist: his unique body composition allows him to contort himself and squeeze into impossible spaces in order to get to his victims. He doesn’t just kill them, though; he takes their livers too. (Blech.) Given his 30-year hibernation period between murder sprees, it took a long time for him to be caught – but after getting paroled, his urges inevitably get the better of him and he’s crushed beneath an escalator while trying to attack Mulder. Bye-bye, Tooms. We’ll never look at an air duct the same way again.

Eve 9 and 10 (“Eve”)

Created as part of a government eugenics experiment to breed humans with superior intellect and strength, the Eve clones were developed during the Cold War, but their extra chromosomes meant that they were also prone to violent, homicidal tendencies. An older-generation Eve clone attempts to modify the project, creating a set of younger Eves that are implanted in mothers under the guise of in vitro fertilization. When the two young girls, living three states apart from one another, both murder their fathers at the exact same time, Mulder and Scully go out to investigate. Eventually the two Eves (who give new meaning to the term “creepy twins”) were remanded to a maximum security mental institution, one that contained all the previous Eve clones too. Eep.

Luther Lee Boggs (“Beyond the Sea”)

Boggs was another example of a seemingly normal human being who may or may not have been in possession of some disturbing abilities. A killer serving his sentence on death row, he encounters Scully at a particularly dark time in her life, claiming to be able to speak to her recently deceased father while also offering to help them with the current whereabouts of another serial murderer. Mulder writes off Boggs as a fraud, but Scully isn’t so sure when Boggs starts offering evidence to the contrary. Boggs is executed by the end of the episode, but actor Brad Dourif is responsible for making him a character whose impact reverberates for fans at an early point in the series.

The Flukeman (“The Host”)

One of the first examples of a terrifying monster, the Flukeman originated from the radioactive soup born out of the Chernobyl explosion. Not quite human, though not quite flatworm, the Flukeman was somewhere in between. It hitches a ride on a Russian freighter before making its way to New Jersey of all places, where it begins to bite unsuspecting victims as a means of implanting them with its larvae. Working solo at this stage, Mulder heads into the sewer system to stop the Flukeman once and for all. The Flukeman’s body is severed in half, but he may not be dead. (An Easter egg in a later episode seems to hint at the possibility that the Flukeman is still at large in some capacity.)

Donnie Pfaster (“Irresistible”, “Orison”)

Donald “Donnie” Pfaster continues the trend of being among the creepiest X-Files monsters who don’t have any special abilities at all.. Pfaster was what was known as a “death fetishist,” meaning that he had some particular… tendencies when it came to dead women. Working at a funeral home, he would collect nails and hair from the deceased, but then took to seeking out living victims to carry out his disturbing fantasies. Scully winds up getting kidnapped, though she manages to outlast Pfaster long enough for Mulder to find her. In a later episode, he seeks out Scully again on the grounds of unfinished business, but she shoots him in self-defense. (While the show hinted that Pfaster may not be all that human due to Scully witnessing him in his demon form, this is not made entirely clear before he dies.)

Phyllis Paddock (“Die Hand Die Verletzt”)

Substitute teachers already have a tendency to be odd, but none were as odd (or as unsettling) as Mrs. Paddock. Although she appears human, she is actually an entity of demonic origins who gets summoned to a small town in New Hampshire by the high school PTA. Apparently, they’ve lapsed in their dark religious worship lately, and so the demon takes on the guise of Paddock to carry out the sacrifices that they’ve stopped performing. While she doesn’t exactly work with Mulder and Scully, she gets rid of the demon-worshipping faculty by making them her sacrifices. And who could forget her possessing a giant snake to do her bidding? Never has writing on a chalkboard looked so sinister.

Leonard Betts (“Leonard Betts”)

If you could compare Betts to anything in particular, think of him as a worm. Cut one limb off and he has the ability to regenerate, which leads to some very icky moments over the course of his single episode. In order to maintain his unique power, he also literally eats cancer and has the ability to detect it in others. Later, he informs Scully herself that she “has something [he] needs,” which leads to the devastating reveal that our favorite redheaded FBI agent is sicker than any of us even knew and spins out into an even bigger, sadder arc for Mulder and Scully. Before he can attack Scully for the cancer he desperately needs to consume, she shocks him in the head with a pair of defibrillators, preventing him from regenerating for the last time.

The Peacock Family (“Home”)

The MOTW episode that proved to be the most controversial in X-Files series history, “Home” aired once and only once on television before being pulled from future re-runs, but it is arguably one of the show’s best. The Peacocks not only represented the horrors lurking in middle America, they were also seemingly content to live undisturbed by the rest of the town’s inhabitants until the discovery of a baby’s grave in a nearby baseball field leads Mulder and Scully to investigate. One could argue that the Peacocks were only trying to defend their territory, but the reveal that the adult sons (also deformed through years of inbreeding) were keeping their incapacitated mother in a box underneath the bed was only one of the series of disturbing things that came to light after Mulder and Scully pursued the case further. Mrs. Peacock later escapes with her one surviving son, possibly to find “home” in another unsuspecting town.

Beggar Man (“Badlaa”)

While this episode did rely on some particularly problematic stereotypes, the Beggar Man who pulled himself along by way of a cart with creaky wheels is an indelible image for many X-Files fans. A purported Indian mystic, the Beggar Man had ability to hide inside the stomachs of his victims, even operating their dead bodies to make it appear as if they were still alive before he could leave and eventually hop into the next stomach available. Although Agents Scully and Doggett are able to incapacitate the Beggar Man, he survives to inhabit another unsuspecting rich man getting ready to hop on a plane, implying that he’s continuing his trend of intestinal inhabitation.

Purity/black oil (“Piper Maru”, “Two Fathers”, “The Truth”)

Technically, the black oil was a part of the grander alien-related mythology that made up the bulk of The X-Files (and Mulder’s obsession), but its capabilities were some of the most terrifying within the show. It had the power to infect humans and then influence them to do its will, but the black oil didn’t stop at the modern human race either. At one point, Scully gets her science on and determines that the virus had infected primitive man as well, lying dormant during the Ice Age until it was reinvigorated thousands of years later. While the black oil initially seemed impossible to fight, a vaccine is later developed which cures the infected, including Scully, who contracts the virus after being stung by that dang bee before she can smooch Mulder in the first X-Files movie. (We’ll never forget or forgive you, bee.)

What monsters scared yo uthe most from The X-Files? What did we miss? Let us know in the comments below.

Images via: 20th Century Fox

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