The X-Filesa sci/fi TV series with episodes stretching from 1993 to 2018, is nothing short of an American treasure. In addition to the TV series, two feature films have been released: The X-Files, released in 1998, and X-Files: I Want to Believe, released in 2008.

The point is, Americans just can't get enough of the good-looking FBI duo and their paranormal investigations, even when the storylines make absolutely zero sense. Over the years, The X-Files has had its fair share of aliens and humanoid antagonists, but some monsters on the show are a little (or a LOT) more thought out than others. Here are 5 of the best monsters on X-Files (and 5 of the worst).

One Of The Best: The Flukeman

Every X-Files fan remembers the Flukeman, a half-man, half-flukeworm monster revealed in season 2's second episode, "The Host." If his slimy, suction-cupped face isn't bad enough, what he did to his victims truly is the thing of nightmares.

The Flukeman transmitted its larvae through its bite, and victims would complain of a foul taste in their mouth for several hours before throwing up a...wait for it...full sized flukeworm a few hours later. Ah, the power of the New Jersey sewage system.

One Of The Best: Eugene Victor Tooms

Eugene Victor Tooms - The X-Files

Eugene Victor Tooms appeared in the first season in not one, but TWO episodes: episode 3, "Squeeze," and episode 21, "Tooms." It's not often that an X-Files villain is popular enough to make it out of one episode alive! Unlike Flukeman, Eugene looks like a regular man, but he has the ability to stretch his body out and squeeze into tiny spaces.

He also has an incredibly low metabolic rate, allowing him to hibernate for thirty years at a time. In between his hibernation periods, Eugene murders exactly five people, remove their livers with his bare hands, and eats them. Lovely.

One Of The Best: Leonard Betts

Leonard Betts was introduced on the twelfth episode of the fourth season of The X-Files in an episode appropriately titled, "Leonard Betts." Interestingly, this was the most watched episode of The X-Files as it aired directly after Super Bowl XXXL.

After being decapitated in a car accident, Leonard Betts (real name Albert Tanner) is able to re-grow his own body parts like a lizard. When Mulder looks into it, he discovers that Betts acquires his powers of regeneration by killing cancer patients and eating their cancerous tissue. Ironically, it was his pursuit of Scully that tipped her off about her diagnosis.

One Of The Best: Badlaa

In the tenth episode of season 8, Mulder and Scully piece together evidence of a murdering Indian mystic (Badlaa) who hides in the stomachs of his victims. In the opening scene, an overweight businessman dismisses a legless beggar while at the airport in Mumbai, India.

The beggar (a Siddhi mystic) attacks and kills the man in the bathroom, yet somehow manages to crawl into his stomach and hitch a ride to Washington, D.C. by making himself invisible or appearing as a different person. Chilling.

One Of The Best: The Peacock Family

In episode 2 of season 4, titled "Home," viewers were introduced to the Peacock family, a group of homicidal inbred mutants that were just as frightening as they appeared.

In fact, the episode was so graphic and disturbing that it was the first of the series to receive a viewer discretion warning, is widely regarded as the scariest episode ever made, and was literally banned from television for three years. There's incest, a deformed dead baby, and a limbless woman who lives on a trolley beneath the bed.

One Of The Worst: Betty

In season 4, episode 13, titled "Never Again," X-Files writers really went above and beyond in terms of ridiculousness with Betty, an evil winking pin-up girl who just happened to be a tattoo.  After a man named Ed Jerse gets a divorce, he has Betty tattooed on his arm, along with the words "never again." Betty ends up being some kind of weird tattoo monster who taunts Jerse and coerces him to murder women.

In the end, Jerse goes on a date with Scully and resists the urge to murder her by burning the tattoo off of his arm. Um...so why didn't he do that before? Ever heard of tattoo removal? Not the best writing the show has ever seen, that's for sure.

One Of The Worst: The Kathy Griffin Twins

Betty Templeton and Lulu Pfeiffer (a.k.a. The Kathy Griffin twins) appear in season seven in an episode titled "Fight Club," also known as one of the worst episodes ever created (surprise, surprise). Betty Templeton and Lulu Pfeiffer are the twin daughters of an enraged convict via sperm donation, and both girls inherited his mood.

Every time they are close to one another, people around them fly into a rage and mayhem ensues. In the scene above, the "doppelgängers" bring about total chaos at a wrestling arena. Honestly, there's not much more to it than that.

One Of The Worst: Amish Aliens

"Gender Bender" is the fourteenth episode of the first season of The X-Files, and it doesn't get crazier than this. In the episode, Mulder and Scully investigate an Amish community called the Kindred, who appear to have the ability to switch gender and literally kill people with an overdose of their ridiculously powerful pheromones. Yep.

But wait, it gets weirder. Mulder has to intervene before Scully is seduced by an Amish piece of man meat, who actually isn't a man at all because they're ALIENS. Yes, the kind from Space. Makes total sense.

One Of The Worst: Virgil Incanto, The Fatpire

"2Shy" is the sixth episode of the third season in which women disappear after meeting someone in Internet chat rooms. Is it a serial killer? No, that's not nearly weird enough. The killer, who goes by the alias Virgil Incanto, is a bonafide "Fatpire" who communicates with overweight women via the internet, takes them on dates, and then literally sucks the fat right out of their bodies.

It's never really explained WHY this particular monster needs fat to survive, but after he's caught he tells authorities that he gave them what they wanted and they gave him what he needed.

One Of The Worst: Small Potatoes

Babies with tails are weird, but the monster in season four's twentieth episode, titled "Small Potatoes," is even weirder. Eddie Van Blundht is a janitor/mutant in West Virginia  (of course) who has the ability to transform into any man he wants thanks to some weird muscle trick that makes zero sense.

After posing as the husband to a bunch of women in town, a slew of babies are born sporting a tail, a birth defect unique to people in Eddie's family. This led to his capture, but not before Eddie almost ended up seducing Scully when disguised as (GASP!) Mulder.

NEXT: Project Blue Book Review: History's UFO Drama Almost Scratches That X-Files Itch