In the early years of the series, Mulder is a firm believer in extraterrestrials and Scully is skeptical. In real life this is the opposite, David Duchovny being the skeptic and Gillian Anderson the believer.
The famous echoing chord from the theme music was a fluke. Composer Mark Snow accidentally rested his elbow on his keyboard with the echo function on and he liked the resulting sound so much he wrote the theme around it.
When Gillian Anderson got pregnant at the start of the second season, some network executives wanted her role recast. Executive Producer Chris Carter adamantly refused their request.
When casting the role of the Cigarette Smoking Man, the producers had no idea the character would turn into a major role in the series. When the character became more prominent, they worried that William B. Davis, who had only been cast as an extra, would not be able to carry the part. As it turned out, Davis, who is one of the most respected acting teachers in Canada, impressed series creator Chris Carter so much that he made the Cigarette Smoking Man the main villain of the series.
Chris Carter wanted the show to end after the fifth season, when his original contract, as well as those of Gillian Anderson and David Duchovny expired. Carter wanted to continue the story in a series of feature films, starting with The X Files (1998). The Fox Network, however, found demand for the show too high to cancel the series, so they instead mandated the film to fit in between series five and six of the show. Carter found writing seasons five and six as well as the film very difficult, as he had to craft a screenplay that would not require the audience to have seen the show to understand it, and episodes of the series that would tie in to the film, but not rely directly on the film's plot to make sense.
During the opening titles, in the Mulder and Scully's FBI ID badges can be read "Federal Bureau of Justice, United States Department of Investigation." This alteration was necessary as making a fake FBI badge, even for fictional purposes, is illegal. The real-life quote is: "Federal Bureau of Investigation, United States Department of Justice."
Despite their chemistry and the deliberately slow-burning sexual tension of their characters, both David Duchovny and Gillian Anderson have admitted that they were less close and bickered with each other due to the long hours of shooting in Vancouver during the show's initial run. After the show ended in 2002 they increased their natural rapport, and now consider themselves great friends and closer to each other than their spouses.
Props from Mulder's X-Files office are currently preserved and on display at the Hollywood Entertainment Museum in Los Angeles. According to the museum, the famous I Want to Believe UFO poster from the office continually had to be replaced as copies kept disappearing from the set. The poster on display at the museum is reportedly one of the last available copies of the original set-used posters.
Gillian Anderson has stated that she based her approach to the role of Dana Scully on Jodie Foster's performance as Clarice Starling in The Silence of the Lambs (1991). Ironically, a contractual obligation to "The X-Files" prohibiting her from playing an FBI agent in any other role prevented her from being offered the part of Clarice Starling the "Silence" sequel, Hannibal (2001).
William B. Davis, who plays the Cigarette Smoking Man, was actually the acting teacher of Lucy Lawless, who plays Shannon McMahon.
Dana Scully was named after the famous sports journalist Vin Scully. Mulder is the maiden name of Chris Carter's mother.
In one episode Scully tells Mulder (David Duchovny) that she thinks Téa Leoni has a crush on him, to which Mulder responds, "How could Téa Leoni have a crush on me?" In real life, Leoni and Duchovny were married.
The series' science consultant, Anne Simon, a virologist at the University of Massachusetts, wrote a non-fiction book in 1999 titled "The Real Science Behind the X-Files: Microbes, Meteorites and Mutants".
The line "The truth is out there", at the end of the opening credits, was ranked #9 in TV Guide's list of "TV's 20 Top Catchphrases" (21-27 August 2005 issue).
Mitch Pileggi (Skinner) met his wife Arlene Warren on the set of the series while she was Gillian Anderson's (Scully) stand-in. Later in the series she got some screen time as Skinner's secretary, Arlene.
Chris Carter lists All the President's Men (1976) as one of his inspirations for the series. There are numerous references to the film, including the shadowy informer Deep Throat, meetings in underground parking garages and hints at conspiracies which stretch all the way to the FBI.
Gillian Anderson has declared several times that her favorite episode is "Bad Blood" and David Duchovny that his favorite end in an episode is 'Postmodern Prometheus'', in which Mulder and Scully dance together. Also, they both agree that the third season episode "Teso Dos Bichos" is the worst one, with Anderson calling it "that one episode about killer pussycats".
The character Leyla Harrison was named after a writer of The X-Files Internet fan-fiction who died of cancer in February 2001. The fictional Leyla Harrison was a fan of Mulder's and Scully's, having spent her time in the FBI poring over their expense reports (in much the same way that Internet fans of the show examined the minute nuances of every episode).
The series does not show episode titles on-screen. While this was not unusual even in 1993 (though it is more commonplace in 2004 when virtually no American dramatic TV series display episode titles), what is unusual is that many fans learned episode titles as well as advance plot information via the Internet. The X-Files (1993) was one of the first TV series to be so promoted.
The recurring character Cigarette Smoking Man was never given a name until late in the series. He is referred to as Cancerman in some early episodes. The show's fans took to referring to him as simply CSM.
During the last season of the show, the opening credits included a shot of a list of "FBI Contacts, Witnesses, and Contributors." The names on the list were actually the screen names of posters on the official "X-Files" message board and changed with each new episode that season. Other names on the list were anagrams of characters on the show.
David Duchovny originally suggested Jennifer Beals, his former classmate at Yale, for the lead female role.
Rebecca Toolan, who plays Fox Mulder's mother, is in reality only one year older than David Duchovny.
Network executives originally wanted a "taller, leggier, blonder and breastier" actress for the role of Dana Scully. At one point in pre-production of the first season, Pamela Anderson was attached to the role, but series creator Chris Carter, who wanted a more cerebral character instead of a more physical one, flatly rejected her. When auditions for the character were finally held, Gillian Anderson was one of the actresses who tested for the part. Carter lobbied for her to be picked, eventually going so far as to talk with her in secret to give her tips on how to get the part., which she was eventually awarded.
Chris Carter has cited Moonlighting (1985) as an influence on this show, specifically the relationship between Mulder and Scully. Carter also has said that the show is an example of how not to further the story, as the sexual tension between the two leads should never be resolved. In spite of this, he always has admitted that Scully loves Mulder and Mulder loves Scully, although he is not very open to a romantic relationship between them being more agree with a platonic love for them.
Lucy Lawless' character Shannon McMahon was meant to become a major recurring character in the show's final season. A high-risk pregnancy, however, forced Lawless to leave the show after only two appearances.
The first five seasons of the show were filmed in Vancouver, British Columbia, Canada. The show often cast local Canadian actors in guest and secondary roles, often reusing the same actors in different parts in multiple episodes. The most prominent example of this was Nicholas Lea, who appeared in a guest role in Season One before being cast in the unconnected, more prominent role of Alex Krycek starting in Season Two, but there are many other examples of local actors who had multiple roles over the course of several different episodes, including J.B. Bivens, Lorena Gale, Gillian Barber, Forbes Angus, Larry Musser, Harrison Coe, Hrothgar Mathews, P. Lynn Johnson, and Doug Abrahams (among many others). Each of these appeared in three or more episodes, each time as a different character (Barber played three characters in four episodes).
Chris Carter based the character of the Cigarette Smoking Man on E. Howard Hunt, while William B. Davis has cited Adolf Hitler and Saddam Hussein as inspiration for his performance.
Nicholas Lea, who plays the traitorous agent Alex Krycek, does all his own stunt work.
The character Sen. Richard Matheson was an homage to noted sci-fi writer Richard Matheson, whose writing inspired Kolchak: The Night Stalker (1974), the show that inspired Chris Carter to create this series.
Mulder's sister Samantha was abducted while she and Fox were watching an episode of The Magician (1973). When Patricia Hearst was kidnapped by the SLA, she was watching "The Magician" with her boyfriend Steven Weed.
Several news sources reported that Gillian Anderson was originally offered only half of David Duchovny's salary to return as Dana Scully for Season 10. "The Daily Beast" interviewed Anderson about this, and she said, "'I'm surprised that more [interviewers] haven't brought that up because it's the truth". Anderson said of the pay disparity, first disclosed in "The Hollywood Reporter", 'Especially in this climate of women talking about the reality of [unequal pay] in this business, I think it's important that it gets heard and voiced. It was shocking to me, given all the work that I had done in the past to get us to be paid fairly. I worked really hard toward that and finally got somewhere with it. Even in interviews in the last few years, people have said to me, 'I can't believe that happened, how did you feel about it, that is insane'. And my response always was, 'That was then, this is now'. And then it happened again! I don't even know what to say about it . . . It is . . . sad . . . It is sad". They eventually received equal pay for the series.
Scully's family has a thing for "Moby Dick": Scully is called Starbuck by her father, her dog's name is Queequeg, and she calls her father Captain Ahab. In 2010, Gillian Anderson, who played Scully, appeared in a version of the novel (Moby Dick (2011)) that also starred Ethan Hawke, Donald Sutherland, and William Hurt.)
Mulder saw Edward D. Wood Jr.'s Plan 9 from Outer Space (1959) 42 times. He also lives in apartment number 42. 42 is the answer to life, the universe, and everything from Douglas Adams's "The Hitchhiker's Guide to the Galaxy", another cult sci-fi story.
Comedian Kumail Nanjiani (known for shows such as Silicon Valley (2014) and The Meltdown with Jonah and Kumail (2014)), who has a role on the reboot of the series, is also a devoted X-Phile who hosts "The X-Files Files," a podcast on which he discusses and analyzes in detail each episode of the original series. During filming, he was chatting with Gillian Anderson and David Duchovny in a production tent in the middle of the night when they asked why he wasn't recording the conversation for his podcast--so he did. At their urging, he asked them about which episodes of the show they thought were the worst. Anderson listed "Space," "Fire," the episode she first called "The Cat One--Los Lobos Tostitos" before Duchovny "corrected" her and said "Tesos Tostados" and Nanjiani provided the actual name of that episode, "Teso dos Bichos." Duchovny identified "the chupacabra episode" ("El Mundo Gira") as one of his worst.
When David Duchovny went to the casting for Fox Mulder, he wore a tie with little pink pigs in it. He later claimed that it was the key to his getting the part.
The character Fox Mulder was ranked #7 in TV Guide's list of the "25 Greatest Sci-Fi Legends" (1 August 2004 issue).
Robert Patrick, who plays Special Agent John Doggett, is the brother of Richard Patrick, the lead singer of Filter. Filter's music has appeared on the TV soundtrack, "Songs in the Key of X", and the The X Files (1998) movie soundtrack.
Adam Baldwin, Lou Diamond Phillips, Bruce Campbell and Dean Cain all auditioned for the role of John Doggett.
Recurring use of the numbers: 1013 - Ten Thirteen is the name of Chris Carter's production company; his birthday is 13 October 1956. 1013 is also the silo number that Alex Krycek is locked into in season 3, and 10:13 is the time where start some episodes (or a scene that's dated at this time). The number 1121 also appears often; it is creator Chris Carter's wife, Dori's, birthday.
Callum Keith Rennie turned down the role of Alex Krycek, not wanting to commit to a television series at the time. He later accepted a role in The X Files: I Want to Believe (2008).
At 29, Gillian Anderson was the first actress to win an Emmy, a Golden Globe and a SAG Award in the same year, and the youngest actress to win a Primetime Emmy Award for Outstanding Lead Actress in a Drama Series since Lindsay Wagner won at the age of 28 in 1977 for The Bionic Woman (1976).
When Gillian Anderson found out she was pregnant only a few months after the show began and it started to become a huge success, she had told David Duchovny before she told the producers, and they were all extremely supportive, even going so far as to find a story arc that would keep her in the show until shortly before she gave birth. Series creator Chris Carter would not replace her with another actress. His reward was being named Anderson's daughter's godfather.
The younger son of Gillian Anderson is named Felix, which contains exactly the same letters as "X File". She got pregnant during the filming of the second movie. Her daughter, Piper Anderson-Klotz, has an episode named after her.
The Lone Gunmen characters became so popular that they were briefly given their own short-lived series, The Lone Gunmen (2001).
Although David Duchovny had been asked many times to have Gillian Anderson guest-star in an episode of his series Californication (2007), he has said that he would never do that because he wanted to preserve their special relationship as Mulder and Scully.
Fox Mulder's first word was "JFK". Curiously, David Duchovny actually studied with JFK's son, John Kennedy Jr..
Former series writers Vince Gilligan and Frank Spotnitz were asked to return for the revival, but had to turn down the offer due to scheduling conflicts with other projects.
Full names of the two main characters are Fox William Mulder and Dana Katherine Scully.
Both David Duchovny and Gillian Anderson have often stated that they share a close and personal link because they are the only two people in the world who have felt and lived the special, unique and intimate relationship between Mulder and Scully and the worldwide phenomenon that the series became.
David Duchovny and Gillian Anderson attended the Golden Globes ceremony together in 1997 and were holding hands the whole night. Both of them won best lead actor/actress in a drama series. Anderson could be seen cursing backstage right after picking up her award while watching Duchovny thanking her when he picked up his; she had just realized that she had forgotten to thank him.
"I made this"--the words spoken over the Ten Thirteen company name--are spoken by Nathan Couturier, son of supervising sound editor Thierry Couturier.
David Duchovny and Gillian Anderson parodied their roles as Mulder and Scully reprising both in animated versions for two cartoon series, The Simpsons (1989) and Eek!stravaganza (1992). In can be seen in The Simpsons: The Springfield Files (1997) (Season 8, Episode 10) and Eek!stravaganza: Eek Space 9 (1995) (Season 4, Episode 9).
William B. Davis has (jokingly) expressed his viewpoint that his character, Cigarrette-Smoking Man, is really the hero of the series, not the villain.
Vince Gilligan, one of the most beloved writers of the series by both the fans and the critics and future creator of Breaking Bad (2008), usually refers to this series as his favorite job ever.
This series' popularity coincided with the growth of the internet, so when a new episode aired, fans chatted and discussed every detail of it online. The writers knew it and used it. The series' fans helped to create such phenomena as "fanfiction" and such terminology as "shippers.
Mitch Pileggi, who had a semi-regular role as Skinner, would later get a recurring role on Supernatural (2005) as Sam and Dean's grandfather, Samuel Winchester. "Supernatural" is often referred to as an "X-Files" clone.
Being too young for the part, Gillian Anderson lied about her real age when she auditioned for it, saying that she was four years older than she actually was.
According to Gillian Anderson, David Duchovny hit on her when they first met but he claims not to remember.
In the UK Twentieth Century-Fox Home Entertainment released new "Mytharc" multi-part episodes as edited-together TV movies on VHS in the mid 1990s. However, these tapes (which usually took the title of just one of the episodes comprising them but were sometimes completely re-named) were extremely expensive and released as numbered "Files" in the wrong order. For example "File 3: Abduction" ("Duane Barry"/"Ascension"/"One Beath") confusingly came after "File 1: The Unopened File" ("Anasazi"/"The Blessing Way"/"Paper Clip"). Although by the third season most mythology episodes were multi- part stories, important plot information relating to the conspiracy could still sometimes only be found in the unavailable standalone episodes to further confuse viewers of these releases. Also, "Colony"/"Endgame" and "Piper Maru"/"Apocrypha" were seemingly forgotten to be included in the series until long after many later episodes.
Mulder's middle name is William and Scully's is Katherine, which are the names of creator Chris Carter's parents.
When some important character was going to die, Chris Carter used to include in his/her script copy one note saying "Nobody dies in The X Files". In fact, he kept his word many times, returning these characters in special apparitions.
Bree Sharp's hit "Why Don't You Love Me, David Duchovny?" speaks about her love for Duchovny and Mulder. Many members of the crew and celebrities like Brad Pitt, Whoopi Goldberg, George Clooney, Alex Trebek, KISS and Gillian Anderson appear in the video of the song. Anderson lip-syncs, "I'm gonna kill Scully".
Chris Carter has said that the series is told from the point of view of Scully, which is the point of view of the audience.
Robert Patrick could not reprise the role of John Doggett for the tenth season due to his work in the TV series Scorpion (2014).
When Agents Miller and Einstein are first introduced in the 10th season, there are several jokes and references that indicate that they are meant to be analogues of Mulder and Scully's younger selves, including Miller's credulity in contrast with Einstein's skepticism and Einstein's red hair and science-related name. The name "Miller" is also a clue to this; the last name "Mulder" originally comes from a Dutch word that means "miller" (that is, a person who runs a grain-processing mill).
Brad Follmer, the character played by Cary Elwes, is named after creator Chris Carter's writing assistant, Brad Follmer.
Christine Willes, who played FBI agent/therapist Karen Kosseff (aka Scully's counselor in Seasons 2 and 4), plays hospital head Sister Mary in the revival.
Cigarette-Smoking Man smokes the fictional brand Morley, inspired by the real-life brand Marlboro (a division of Atria's Phillip Morris USA).
Mulder graduated Cum Laude from Oxford University (psychology) and was the first one of his class at the FBI Academy in Quantico, VA. Scully studied physics and medicine but was recruited by the FBI. She chose to become an FBI agent rather than a medical doctor.
All the episodes written by John Shiban, Vince Gilligan and Frank Spotnitz together have a character named John Gillnitz as a kind of secret signature.
The name of the female lead in the series, Dana Scully, is also found in Anne Tyler's bestselling 1985 novel "The Accidental Tourist".
Several actors and actresses who co-starred or guest-starred would eventually go on to prominent co-starring or recurring roles in Stargate SG-1 (1997) and/or its spin-offs: Amanda Tapping (Col. Carter); Don S. Davis (Gen. Hammond); Mitch Pileggi (Col. Caldwell); Teryl Rothery (Dr. Janet Frasier); Colin Cunningham (Maj. Paul Davis); Megan Leitch (Capt. Ke'ra); Steven Williams (Gen. Vidrine); Bill Dow (Dr. Bill Lee); Elizabeth Rosen (Lt. Jennifer Hailey); Jamil Walker Smith (MSgt. Ronald Greer); Willie Garson (Marty Lloyd).
When asked if she would play a Hank's (David Duchovny) lover in Californication (2007), Gillian Anderson said that she would do it for free.
The character Dana Scully was named after Dodger broadcaster Vin Scully, and John Doggett was named after Vin's broadcasting partner Jerry Doggett.
The addition of the Skinner character in The X-Files: Tooms (1994) was fortuitous for actor Mitch Pileggi, as the part was to go to the actor who played Blevings but who was busy when this episode was to be shot, and it was given to Pileggi instead. His chemistry with Mulder, Scully and the CSM resulted in Skinner being made a permanent member of the cast of characters.
Many of the cast's real-life partners worked on the show: Perrey Reeves, David Duchovny's girlfriend for two years, played his lover in "3". Maggie Wheeler and Lucy Liu, both of whom dated Duchovny, appeared in "Born Again" and "Hell's Money", respectively. Even his former wife, Téa Leoni, played herself in "Hollywood AD". Gillian Anderson dated Rodney Rowland, who appeared in "Never Again", for over a year. She also dated Adrian Hughes, who played one of the Peacocks in "Home". She was married to, and had a daughter with, Clyde Klotz, the show's art director, after they met at the beginning of the series. Mitch Pileggi met his wife, Arlene Pilleggi, on the set of the show--she played his secretary and was Gillian Anderson's double. Robert Patrick's wife played his character John Doggett's wife in the final season.
Although the Cigarette Smoking Man is obviously famous for chain smoking cigarettes, he only utters the word "cigarette" one time during the show's run. William B. Davis, who plays him, was a former smoker who had not smoked since 1973, 20 years before he was cast for the series. At the beginning of the show the cigarettes he smoked were real, until he became aware that he was having cravings for tobacco when not filming. At his request, the cigarettes used from then on were herbal.
David Duchovny also played a government agent in another cult series with paranormal overtones, David Lynch's Twin Peaks (1990). Don S. Davis, who plays Scully's father on this series, also played a military figure on that series.
The full names of The Lone Gunmen are: John Fitzgerald 'J.F.' Byers (played by Bruce Harwood). Richard 'Ringo' Langly (played by Dean Haglund); Melvin Frohike (played by Tom Braidwood).
According to Chris Carter, David Duchovny hates that Mulder is a hero who always knows everything because this wouldn't be realistic, so he wants that Mulder makes mistakes.
There were many stars who appeared in this series before they became famous: Giovanni Ribisi, Jack Black, Lucy Liu, Ryan Reynolds, Luke Wilson, Aaron Paul, Seth Green, Felicity Huffman, Michael Bublé, Terry O'Quinn, Bryan Cranston, Willie Garson. The series also attracted a lot of actors who were quite famous even before the series came on: Jodie Foster, Cary Elwes, Robert Patrick, John Neville, Peter Boyle, Burt Reynolds, Frances Fisher, Roy Thinnes, Minnie Driver, Garry Shandling, Lance Henriksen, Lily Tomlin, Edward Asner, Lily Taylor and Mimi Rogers.
Vince Gilligan frequently makes references to his girlfriend, Holly Rice, in all the episodes he writes.
Catatonia issued a song called "The X Files" on its "International Velvet" album in 1998. It was one of the biggest hits of that year.
When Mulder awakes in the cemetery towards the end of Season 10, Episode 3, The X-Files: Mulder & Scully Meet the Were-Monster (2016), he is lying on the grave of someone named "Kim Manners". It's a tribute to Kim Manners, one of the directors of the show, who died of lung cancer in 2009.
According to Robert Patrick, Doggett might be his favorite character in his career.
During the original series Mulder lives in Alexandria, VA, and Scully in Georgetown, DC.
In a 2015 interview with National Public Radio, composer Mark Snow said that when he was originally trying to compose the theme song, after he sent creator Chris Carter a few ideas, which Carter rejected, Carter sent Snow the 1985 song "How Soon Is Now?" by The Smiths, saying, "I just love these guitars. Listen to this song, and see if it inspires something." Snow also said that he got the idea for the whistling element of the theme from an old Proteus sample called "Whistling Joe," but the whistle actually heard in the recording of the theme is bolstered by Snow's wife, who was a particularly strong whistler.
Gillian Anderson and Annabeth Gish gave birth to their sons ten days apart. Anderson had Felix, her third child, on 15th October 2008 and Gish delivered Enzo, her second son, on the 25th.
One of the first television series to switch to a 16:9 widescreen aspect ratio, beginning with its fifth season in 1997 at the insistence of Chris Carter to give the show a more cinematic feel, though Fox aired the episodes cropped to 4:3 while the original 16:9 versions were released on DVD. The series was remastered in 16:9 high definition in 2014, converting the first four seasons to widescreen as well, generally through cropping.
Contrary to popular belief, ratings did not go down during season 6, they actually went up. It was the the viewership that went down between seasons 5 and 6.
Chris Carter usually refers to the chemistry between Anderson and Duchovny as "a rare miracle we were blessed with".
The two main characters of the TV series The 4400 (2004), Tom Baldwin (Joel Gretsch) and Diana Skouris (Jacqueline McKenzie), are inspired in Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson). It's more evident in the names of the feminine roles.
Mulder's fondness for porn is largely known and became an in-joke in the series; but he seems to have a thing for classic cinema, as far as we see him watching classical movies in multiple episodes.
Given the height difference between Duchovny and Anderson, she used to stand on a box dubbed the "Gilly Board." According to Anderson, sometimes she used to forget about its presence and trip over it.
The conexión between Mulder and Scully is so powerful that according to Gillian Anderson every time they hold hands is like making love in any other series (1998 during Fight to the Future promotion).
Among the most famous cliches in the tons of fanfics written since the series started are: Scully is known as Ice Queen in the FBI. Mulder has oral fixation. There is a poll in the FBI regarding when Mulder and Scully will consume their relationship. Mulder and Scully always have a connection door between their rooms in the motels. Mulder and Scully are forced to share a bed. Charlie, Scully's little brother, is a nice guy. Skinner always knew about Mulder and Scully secret romantic relationship.
Gillian Anderson has the record of appearing in the most episodes of the series missing only the following five: Mulder's solo episode The X-Files: 3 (1994) (although Scully is briefly referred to in the dialogue), Skinner's episode The X-Files: Zero Sum (1997), The Lone Gunmen's episode The X-Files: Unusual Suspects (1997), the flashback episode The X-Files: Travelers (1998) and Agent Doggett's solo episode The X-Files: The Gift (2001).
Former director/producer Rob Bowman didn't return to direct the series, because in a roundtable discussion as to whether or not to do another "X-Files" feature film, it was decided that a six-episode mini-series would be able to go more in depth with previous story arcs and continuity from the original series and first film.
In keeping with the original series run's practice of reusing Canadian character actors in multiple unrelated parts, Hiro Kanagawa, Christine Willes and Alex Diakun each appeared in one of the three first episodes of the long-delayed "reboot" (aka Season Ten) aired in 2016. Kanagawa played two different characters in the second and fourth seasons; Wiles had the small but recurring role of FBI Agent Karen E. Kosseff (Scully's therapist) in three different episodes; and Diakun played four different characters in the second and third seasons and the second movie.
According to Scully, Mulder's nickname during his training in the FBI's Academy was "Spooky", because of his excessive passion about supernatural phenomenons.
Gillian Anderson has an explosive, uncontrollable and infectious laughter so, during the filming they frecuently had to stop when she had a fit of laughter until they all could keep going.
According to Gillian Anderson, at the beggining of the series she was supposed to walk one or two steps behind Mulder in order to give him the prominence. She clearly won her own position in a few episodes.
Mulder's line, "Sometimes the only sane response to an insane world is insanity", is similar to a quote from Philip K. Dick's science-fiction novel"Valis".
Most of the fans want the relationship between Mulder and Scully and they are named shippers and most reciently Sculder, as noromo are the fans that don't want their romance. After the fans of The X Files started using the term "shipper", this term was used in other fandoms. In the same way, fans that believe in a romance between Duchovny and Anderson are named snoggers or Gillovny.
Dana Scully was named after famous sports journalist Vin Scully. Mulder is the maiden name of series creator Chris Carter's mother and Fox was the name of a boy he went to school with.
Although they don't share scenes in the series, it reunites two actors from Walt Disney's Wonderful World of Color: Earth Star Voyager: Part 1 (1988): Peter Donat and Bruce Harwood. Donat and Harwood played Adm. Beasley and Dr. Eugene Leland, respectively; in this series they played Mulder's father and J.F. Byers (one of the Lone Gunmen).
The main theme song was often used as a background music in Wild Angel (1998), an Argentinian television series.
The tenth season mixes its own mythology with "Monster of the Week" episodes, being just the first and last episode of the season dedicated to the mythology, and the other four to the Monster of the Week.
As far as the director/productor Bob Goodwin was married to Sheila Larken, who stared as Scully's mother, Gillian Anderson and he used to refered each other as father and daughter.
David Duchovny textually declared "I never, ever, ever cook. And I would never eat something I might cook". Mulder seems to have similar abilities since we have never seen him cooking, he usually eats fast food and the few times we saw him in his kitchen his fridge was almost empty or his food is expired.
The red speedo that Mulder wears in his scene with Krycek at the beginning of the episode became in a sexual icon, so, many years after that, it still is the object of multiple jokes of the fans and the crew, particularly his partner. Anderson, among other things spoke about his size or was photographed dressed with other red speedo in a couch. Darin Morgan also wrote a gag in the 10th season so Mulder could wear it again and he was admired for it by a special character.
Over the years The Scully effect, that consists in how young women have chosen to join to law enforcement and medicine as a result of their admiration for the inner strength of Scully, has grown all over the world.
Regarding to Scullys wardrobe in the first seasons, according to Gillian Anderson nobody paid attention to her then. However, she has been much more involved in this aspect of her character in the revival seasons.
Laurie Holden, who played the recurring character Marita Covarrubias from seasons 4-9 (from 1996-02), does not reprise her character in the tenth season.
The X Files is the big germ of Breaking Bad. Vince Gilligan not only exploded here as a fantastic writer, becoming in one of the favourite series of both the audience and the critics, found here his most relevant collaborators but also presented the basic characteristics of Walter White in characters like Robert Modell.
David Duchovny and Gillian Anderson's birthdays are only two days apart, even though he is eight years older.
Piper, Gillian Anderson's daughter, was literally raised on the set of The X Files, so when she saw a monster or something that would scare any other child she used to be curious and ask if she could touch it. Regarding this situation, David Duchovny used to say he was lucky for not being the one who would have to pay for her therapist. On the contrary, when Gillian wanted to her younger sons see her in the series she showed them Bad Blood, one of the most comic episodes, it only gave them nightmares.