Years before Supernatural became a sensation, X-Files proved to be a ratings hit for viewers when it comes to dense mythology mixed with Monster of the Week episodes. In the series, Mulder was an FBI agent who was obsessed with searching for aliens while Scully was his partner, a disbeliever when they started.
As with Supernatural, there were great Monsters of the Week episodes that were often even better than the mythology episodes themselves. This is where the scariest episodes also resided, featuring many horrifying monsters, creepy storylines, and disturbing moments.
Updated on July 1st, 2021 by Amanda Bruce: Not every fan was happy with the X-Files revival series, but the original series is still looked at fondly by fans. The mythology might not have always made sense, but the scariest threats in the series still hold up nearly three decades later. These particular episodes remain the scariest of the season, though not all of the scary parts of even monsters.
Roadrunners (Season 8, Episode 4)
It's rare that Dana Scully takes on cases alone, and her having no backup in the field is part of what helps build the suspense in "Roadrunners." She investigates a murder that leads her to a cult-like group that gets the better of her.
The group believes that a parasitic worm is a religious messiah, and she almost ends up as another one of their victims. It's one of the few times in the series in which the audience genuinely believes Scully could be taken out of the equation.
Die Hand Die Verletzt (Season 2, Episode 14)
In the late '80s and early '90s, a lot of movies and television series used storylines centered around the occult to sell horror, and this episode is one of the best instances of that.
While the initial circumstances of the episode lead Mulder and Scully, and the audience, to believe that teenagers in a small New England town are cut up in their own occult rituals, it turns out that's not the case. It's the adults who are supposed to be looking after them who are. It's also implied that the devil himself comes to town when those worshipping him don't do as he asks. The episode is even left open-ended as the mysterious Mrs. Paddock, the potential stand-in for the devil, just leaves town.
F. Emasculata (Season 2, Episode 22)
Unlike most of the series, this episode doesn't center on an alien conspiracy or a traditional monster of the week. Instead, it centers on a deadly contagion. The scariness of the episode comes from the possibility of it playing out in real life.
A pharmaceutical company tries to experiment with an insect that kills its hosts, but they do so by sending a package to a prison inmate, which causes the contagion to spread as two prisoners escape. Mulder wants to tell the population at large the truth, but the government won't allow it to keep the spread of panic under control. This episode details the kind of conspiracy that feels more believable to the audience than the show's continued covering up of alien abductions.
Sanguinarium (Season 4, Episode 6)
Combining a story about plastic surgery with one about witchcraft, "Sanguinarium" is higher in the gross-out factor than it is the thrills, but it still deserves its spot amongst the scariest episodes.
Mulder and Scully investigate what he thinks is a case of someone using witchcraft to curse doctors or patients, but that's not entirely the case. Instead, the implication is that a plastic surgeon, on the quest for eternal youth, has somehow found it by making some of his patients his victims. It's also left open-ended as he evades the FBI agents on his trail.
Ice (Season 1, Episode 8)
"Ice" is one of the best psychological thrillers The X-Files ever offered its audience, and it did it only a handful of episodes into the series run. Yes, it features a Monster of the Week in the form of a worm that may or may not be extraterrestrial, but the fear builds in the episode because of isolation and a lack of trust.
Mulder and Scully have to investigate an isolated group of researchers in Alaska. Everyone turns on one another, suspecting they're infected by the parasite in question, as they wait for a storm to pass.
Grotesque (Season 3, Episode 13)
The Season 3 episode "Grotesque" saw Mulder mocked by a legendary FBI profiler because of his search for the unknown. This would always lead to bad things, and in this case, it was a case that Mulder was called in to look at involving a man arrested for murder who was drawing gargoyles.
Mulder starts to question his own sanity as the FBI profiler constantly dismisses his ideas, and then the episode shows what happens when a person becomes the monsters that they hunt.
Leonard Betts (Season 4, Episode 14)
The fourth season episode "Leonard Betts" was scary for more than one reason. First up, there is the villain, Leonard Betts. He was a decapitated corpse that got up and walked out of the morgue without his head. He then went home and regrew it, meaning he could change his look and remain free.
However, outside of the fear from the monster itself was his revelation. He stays alive by feeding on cancerous tumors and will rip them out of his victims. When he tells Scully she has cancer, the fears become more than just about the monster.
Eve (Season 1, Episode 11)
There might not be anything scarier than creepy kids, and "Eve" has that terror doubled. This is an episode about genetic testing and cloning, and the clones here are the two twin girls, Teena and Cindy.
This episode dealt with the Litchfield Project and creating super-soldiers, but these two girls are a frightening result. They have telepathic abilities and possess murderous urges. Just imagine if the terrifying twins from The Shining grew up and became killers.
Home (Season 4, Episode 2)
"Home" is a notorious X-Files episode for one big reason. It is the only episode that carried a viewer discretion warning. Despite this, fans were still overly disturbed, and Fox received several complaints from viewers and pulled it from the rotation for a time.
The most disturbing thing is the woman who delivers birth at the start of the episode. The woman had no arms or legs, is kept under the bed, and the baby met a terrible fate too. The family that perpetuates these acts even lives to see another day, escaping at the end of the episode.
Unruhe (Season 4, Episode 4)
The Season 4 episode "Unruhe" is an episode that uses a trope that has been used in movies and TV shows for years. However, The X-Files episode is still frightening despite the familiarity.
The episode is about a person who can influence a photograph using their mind, and they are performing lobotomies of their victims. Scully is kidnapped in this episode, and the final terror in this episode comes in the fact that the killer used a dentist's chair when he lobotomized his victims.
Detour (Season 5, Episode 4)
The scares from the fifth season episode "Detour" comes from the humanity vs. nature idea. There is a seemingly invisible attacker killing people in a National Forest. Having a creature killing that no one can see or understand makes it much scarier than actually seeing a giant monster. The murderous creature just had red eyes, but there is nothing else there to see.
The scariest thing is that Scully shoots the creature, but it disappears, helping make the ending unforgettably scary.
Chinga (Season 5, Episode 10)
The X-Files episode "Chinga" offers up one of the things that scare many people — dolls. This episode has a little girl with a very disturbing doll that actually can say two things, including "Let's have fun" and "I want to play." However, when Chinga says these things, bad things happen.
When Chinga speaks, people nearby mutilate their own faces. With the creepy doll, the little girl, and the carnage that Scully finds, there is a lot in this episode to scare just about any viewer. This was bound to be a scary X-Files episode since Stephen King wrote it.
Irresistible (Season 2, Episode 13)
The scariest villain in X-Files history is a human serial killer named Donnie Pfaster. He is mostly scary because, in his first appearance, he is a killer that looked normal but was terrifying.
Scully said that Pfaster was the look of true evil, and she said this after seeing supernatural monsters. Sadly, when he returned in Season 7, he became an actual monster which made him less frightening, but his first appearance was terrifying.
The Host (Season 2, Episode 2)
If anyone is looking for a disgusting and horrifying creature for horror, the X-Files episode "The Host" is one of the most frightening. The villain is the Flukeman, which is a human-sized larva creature that was created thanks to the fallout from Chernobyl.
It winds up hitching a ride on a Russian freighter and ends up in the New Jersey sewers, where it starts to feed on people. Anyone who watches this will think twice about using a Port-A-Potty.
Squeeze (Season 1, Episode 3)
"Squeeze" features one of the most disturbing villains in X-Files history. Eugene Tooms is one of the few villains to return for a second episode down the line. This was the first Monster of the Week villain, and it set a bar that few episodes after it were able to reach.
Tooms has regenerative abilities and just needs to ingest livers from people before he can hibernate for 30 years without needing another. The episode is scary and disgusting, and one of the best in X-Files history.