The Blair Witch Project

The Blair Witch File by RetroSkater
XF/Blair Witch Project crossover.

The Blair Witch Files by R.J.C.
Before the 1999 Summer Movie season began, Agents Scully and Mulder had a bit of a distraction caused by a certain bootleg video...

The Blair Witch Project: Mulder's on the Case by Raye
The man just can't help himself. Major spoilers for TBWP.

Burkittsville by eponine119
There's something in the woods...

Formerly Blair by Cornflake Girl
Mulder and Scully go looking for the three college students who disappeared in 1994.

Scully and Mulder Project by Divalicious Pink
Mulder and Scully go on a witch hunt of there own.

BTVS and/or Angel

Adventures in Sunnydale by Angel Brown
A crossover between X-Files and Buffy the Vampire Slayer

Evil, My Way by stellar_dust
Spike meets a frightened little girl during his flight from Sunnydale.

Fatherhood 2002 by Xanthe
It isn't easy being a sci-fi dad these days...

Four Days by Sister Moon

Girl's Night Out 2 by Weyer
An assassian, a Slayer, some weird women, a cult and a demon make for an interesting vacation.

Janus by twistedchick
Wesley rescues a one-armed man from demons, and then things get interesting

Now It's Dark series by Jennifer-Oksana
The death of one life leads to the birth of the next.

Shaggy Dog by A Gentleman Of Leisure
After the destruction of Sunnydale, an old friend returns to look for the Slayer and her friends.

The Slayer Files by Mark Safransky
Mulder and Scully are sent to investigate strange occurrences in Sunnydale, California.

The Soul Chronicles by Hardra6
Angel and his crew team up with Scully and hers to track down an elusive Vampire FBI agent

Statistical Anomaly by A Gentleman Of Leisure
What prompted the Initiative come to Sunnydale?

Sunnydale CA by Heidiwax
Mulder and Scully Arrive in Sunnydale to checkout some unusual weather patterns and stumble upon more than they bargain for.

Trusting One Another by KaThErInE-AnNa
Mulder and Scully cross paths with the crew of Buffy (Buffy, Willow, Angel, Giles etc...) to investigate. Investigate what? Take a wild guess. What Else? Vamps!

Vesparys by Nynaeve
Two demons wreak havoc. Mulder and Scully chase down the "X-File" only to discover someone else knows a little something about this sort of "unexplained phenomena".

Winter Beach by Lisby
Just take it as it comes. Set during Mulder's absence in season 9 and immediately after the aborted wedding in Buffy.

The X-Factor by Teresa and Ashley
A bored vampire ropes in a hapless FBI agent to stir up his town. Because Mulder is the agent in question, things don't turn out like they should.

An X-Halloween by apckrfan
Mulder, still presumed dead, gets word from the Gunmen of an entire town, old and young alike; turning into their costumes on All Hallow's Eve and sends for Scully to help him investigate.

Charmed

Ascending by IfIQuitNowTheyWin
One can take them away from the FBI, but the weird and magical are still following Mulder and Scully around. This time, all the way to San Francisco , and there may be a good reason...

Charmed to Meet You by Scully854
Mulder and Scully go to California to solve a murder and are helped by the Charmed Ones.

Charming X-Files by Caleigh R.
Mulder and Scully go to San Francisco to get information on a certain Prue Halliwell that Special Agent Andy Trudeau apparently protected by destroying evidence. There, they find the Charmed ones.

Hubble, Bubble, Toil and Trouble by Reefgirl
Agent's Doggett and Scully got to San Francisco to investigate the murder of Wiccans, on the way they meet the Halliwell sisters.

When in LA by Echo126
After years, Fox decides to visit his cousin, Piper Halliwell, in LA. But what are his reasons?

ER

Rude Awakening by Mic2
Interesting doctors and nurses, a couple of unusual trauma cases, an intriguing case, a little bit of voodoo magic, and you got yourself an X-File.

Just Another Knight by Michelle M
What do you get when you take Mulder, Scully, the ER docs, and a crazed vampire? Read on...

Forever Knight

Infatuation with a Vampire by Fran Glass
X-Files/Forever Knight crossover. While investigating cattle mutilations in Montana, Scully is abducted by a mentally unstable person that Mulder suspects of being a vampire.

Just Another Knight by Michelle M
What do you get when you take Mulder, Scully, the ER docs, and a crazed vampire? Read on...

Paradigm Shift by Linda Stoops and Andrea Brown
An art-theft investigation drags Mulder and Scully into a darker realm than either anticipated, and it will require the aid of a certain Toronto detective and his M.E. friend to bring the female agent back from the edge of vampirism.

Harry Potter
And Chaos Ensued by attackofthejello and Teresa6
No one could have expected the madness that befell Hogwarts when four FBI agents arrived to investigate baby William's potential status as a wizard. Harry & Company spend an action-packed afternoon with Mulder, Scully, Doggett, and Reyes-- chasing Wormtail down, dueling the Malfoys, and discussing the woes of their fanfictional existences. Also, the Agents can't believe who turns up to ruin their day-- in the form of Hogwarts's newest ghost.

Labyrinth

[External Link] The Goblin Market: I. We Must Not Look On Goblin Men by shadow13
Federal Agents Fox Mulder and Dana Scully can't begin to imagine why children are vanishing throughout the country - or why no one seems to remember that they exist at all. Scully has her own theories, but Mulder is inclined to listen to the whispers of the children left behind; whispers about goblins in the night, and their King.

[External Link] The Goblin Market. II. We Must Not Eat Their Fruits by shadow13
When a powerful Senator disappears from his rural cabin, Mulder is quick to believe he's the victim of a bad deal with a certain Goblin King. But if he and Scully are to save the Senator from the Labyrinth, then they need the help of its Champion.

Scooby Doo

Beyond the Sea-Monster by Gail Celio
With a little non-existent extra time on my hands, I've finally fleshed out a twisted idea that falls under the heading "Crossovers from Hell". I give you the rough draft of a short story that answers that age-old question: "What would happen if Agents Mulder and Scully met up with Scooby Doo and his friends?"

Works by Stephen King

Dark Places by Michelle Blankenship
Mulder and Scully investigate the death of an FBI trainee and find themselves drawn into a conspiracy.

The Third Wheel series by DavidB226Morris
After the events at El Rico Air Force Base, Mulder and Scully are reassigned to the X-Files. The catch is that another agent has been reassigned to them

Supernatural

[External Link] Finding Neverland by WildwingSuz
The Winchester brothers get a surprise in the forest while tracking a monster, and Mulder and Scully get an even larger one when they find themselves in a world full of supernatural beings.

The Line by Neoxphile & Faerax
Sam and Dean Winchester meet Mulder and Scully while waiting for the release of the last Harry Potter book

Looking for Salt by dotfic
Sam, Dean, Mulder, Scully, and zombies. Lots of zombies. Any questions?

The Walking Dead

The Dead Files by WildwingSuz
Mulder and Scully discover Rick Grimes’ group during the zombie apocalypse.

X-File DF1013209: The Walking Dead by theexit
They knew something terrible was going to happen in 2012, they just didn’t bargain on this.

Welcome to Night Vale

[External Link] Fox & Dana Visit Night Vale by appleshaush
It's written roughly in the style of a typical Night Vale broadcast; Cecil observes Scully and Mulder's investigative shenanigans, yadda yadda yadda.

[External Link] Fritz Crisler Sends His Regards by stillscape
The truth is out there. Perhaps...perhaps it is even in Night Vale.

Horror Movies

28 by redfox1303
28 Days Later meets X-files and Colonization begins. Follows the Survivors of the apocalypse.

Bride of the Mulder by Brenna Ferry
What happens when our two favorite FBI agents are dropped straight into the classic Ed Wood movie, "Bride of the Monster"? Scully and Mulder investigate rumors of a monster, succumbing to bad dialog and ridiculous characters.

Return to The House on Haunted Hill by Cheri
Mulder and Scully investigate the house on haunted hill after the disappearance of two teenagers

Room 209 by Neoxphile
During the last week of October Scully is asked to take over the case of a comatose little boy. Strange things begin to happen in Our Lady of Sorrows soon after. WIP

Silent Hill by Rose Campion
In the unsure hand of a child, crude loops and wavering lines was scrawled a note. "Daddy," it read, "You said someday we could go back to Silent Hill but we never did. Now I'm here all alone. Luke."

Trinity's Children by devout2David
This takes place after the episode "3" and two years after Scully has returned to Mulder and the X Files. While investigating the murder of friend's daughter from Scully's past, Mulder's own past comes back to haunt him.

Other Assorted Fandoms

And If I Die... by Demeter
((X-Files/Nightmare on Elm Street)

All Through the Night by Merlin Missy
Mulder and Scully come to New York. This is never good.(X-Files/Gargoyles )

Beyond The Truth series: II. High Stakes by Neoxphile
Anita Blake, Vampire Hunter (from the Laurell Hamilton novels) poses as a nanny in Mulder and Scully's home, so she can learn more about a vampire problem in the DC area.

Burned At The Stake by trycee
Mulder and Scully are investigating a modern day Witch who was burned at the stake, an old patient of Hannibal's. The woman's ghost has been seen since her death bursting into flames to horrified on-lookers. Mulder and Scully seek to solve her murder. ((X-Files/Hannibal)

Dirty Minds by Neoxphile
On New Years day 2006, Mulder and Scully's visit to Bon Temps Louisiana alarms some locals. (X-Files/Sookie Stackhouse crossover)

[External Link] Hunger by dhamphir
What happens when a hungry succubus hooks up with a certain redhead? (X-Files/Lost Girl)

[External Link] The In-Between by CrossedBeams
Somewhere between this world and the upside down, between life and death, is a lake. (X-Files/Stranger Things)

Quanik by Sarah Stella
Mulder and Scully head north following a series of disappearances in the Maine woods. What they find there is an unusual woman named Smilla and quite possibly an ancient monster carved out of ice. ((X-Files/Smilla's Sense of Snow)

[External Link] Sleeping with the Enemy by alicambs
Someone from England wants to make use of Mulder, and the Consortium want to know why. (X-Files/Ultraviolet, UK)

Something in the Blood by FelineFemme
While a few may be familiar with "The Adventure of the Sussex Vampire," I decided to take a whirl – meshing the world of Sherlock Holmes with the X-Files.

The Umbrella Conspiracy by Jill Valentine STARS
Special Agents Dogget and Reyes are sent to investigate a series of murders in Raccoon City. And, with the aid of two detectives, they soon find themselves trying to survive the many horrors of that city. (Resident Evil/X-Files crossover.)

Wa-a-ay Out There by Gozer
Mulder and Scully and the Real Ghostbusters meet in the swamps of New Jersey, investigating… swamp gas?!?

Zombies by Nialani
Night of the Living Dead meets the X-files