Created by Chris Carter, The X-Files was one of the biggest shows of the 1990s. After its first episode aired in 1993, the series quickly went from a cult following to a breakout hit series. Centered around two FBI agents Fox Mulder and Dana Scully who investigated unsolved cases of the paranormal, X-Files brought conspiracies, alien abductions and bizarre monsters into the mainstream. Often scary, tragic and even hilarious, the show not only was a critical and commercial success, it inspired other TV shows over the years like Fringe, Supernatural and Warehouse 13. It also led to two feature films, comic books and a recent revival of two new seasons.

Behind the scenes, the TV show was anything but smooth. The show suffered from actors fighting, controversial decisions, and increasing pressure to fit the mold of a regular TV show. In the later seasons, fatigue and the loss of major cast members led to a decline, but the show is just as popular as it was decades ago. With the eleventh season of The X-Files airing on Fox, CBR looks back at the original series and the hidden secrets behind its creation and evolution.

15 THE CAST HATED EACH OTHER

On the screen, Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) made the perfect team. Scully's skepticism and scientific background worked perfectly to balance Mulder's open ideas and knowledge of the paranormal. Behind the scenes, things were much less friendly. In fact, the two actors couldn't stand each other.

Both actors later admitted that having to work together for long 18-hour shoots on most days of the week put a strain on their relationship. In fact, Anderson literally said they hated each other. At one point, they refused to speak to each other off-camera and never socialized outside of work. Anderson even neglected to thank or mention Duchovny when she won an award for the show. Since the end of the series, the time apart has healed old wounds and they're friends, especially since reuniting in the revived miniseries.

14 DUCHOVNY VS. FOX

While the TV show made him a superstar, David Duchovny wasn't happy, because he felt he could be a bigger star and make more money without X-Files. Things between Duchovny and 20th Century Fox came to a boil in 1999 when he filed a $25 million dollar lawsuit against the company, claiming it had cost him millions of dollars.

In 1995, Duchovny agreed to extend his contract on X-Files for two more years in exchange for being paid the same in profit participation as series creator Chris Carter, which would have been for millions of dollars. Instead, Fox sold the syndication rights to X-Files to its own affiliates at cheap prices, reducing the profits on paper. At the same time, Fox secretly paid Chris Carter millions of dollars and a commitment to another 13-episode series in exchange for his silence. It was settled out of court.

13 INSPIRED BY FAILURE

The X-Files was inspired by many things, including the movie All The President's Men, the FBI thriller Silence of the Lambs and TV shows like The Twilight Zone. Carter has also cited a little-seen show that barely lasted a season as his greatest influence: Kolchak the Night Stalker. Kolchak was a TV show in 1974 about an investigative reporter who pursued the paranormal. While the original series flopped, the young Chris Carter loved the show and wanted to make something like it.

His idea for a TV show was to change the premise to FBI agents to give them a better reason to be investigating the cases, but keep the anthology-style format of pursuing a different paranormal case every week. That, plus a survey about how millions of Americans believed they'd been abducted by aliens, led to The X-Files.

12 THEY HATED VANCOUVER

Though The X-Files had episodes claiming to be set all over the United States, the vast majority of the show was filmed in Vancouver, British Columbia in Canada. Carter wanted the show filmed in Vancouver because it was cheaper than shooting in forests in California (there were a lot of forests in the show) and cold, cloudy environments fit the theme of The X-Files.

However, some of the cast and crew hated Vancouver because it was cold and rainy much of the time. While that allowed for a lot of moody gray skies, it didn't make for enjoyable shoots, especially at night. David Duchovny, in particular, was outspoken about how he didn't like the rain and being away from his wife Tea Leoni for months at a time.

11 THE FBI ALMOST SHUT IT DOWN

The whole idea of the show is built around the FBI. The premise is about a pair of FBI agents and they work within the federal justice system so the show spent a lot of times in a fictional FBI environment. That's why it became a problem that the FBI tried to shut the show down.

When Chris Carter originally approached the FBI about getting information for the show, the agency was pretty dismissive. Later on, as the show came close to airing, the FBI reached out to Carter to demand more information. Carter realized they were concerned about how the agency would be portrayed and worried that the government agency would shut down the production. Fortunately, the FBI came around and not only didn't stop the show but even helped with technical advice. Internally, FBI agents also became big fans of the show.

10 THE THEME WAS AN ACCIDENT

The theme song of The X-Files is one of the most iconic in television history, and it's kind of an accident. The composer Mark Snow was a friend of the executive producer R.W. Goodwin, who suggested Carter hire him, but he took a long time to come up with the theme.

Carter and the producers told Snow they wanted heavy use of synthesizers to give the theme an atmospheric feel. Carter also wanted it simple enough that scared kids could whistle it around a campfire. While struggling to come up with a song, Snow accidentally leaned on his keyboard and turned on the echo effect while playing the four notes that make up the song. He liked the sound of it and added a prerecorded whistle on his synthesizer called "Whistling Joe," which is exactly the whistling tones he ended up using. The rest is history.

9 THEY DIDN'T LISTEN TO SCIENTISTS

It was heavily promoted that X-Files consulted with real scientists to come up with realistic explanations for all the strange things that happen. For instance, the show often consulted with Anne Simon, an American biology professor and scientist. She helped with episodes like "The Erlenmeyer Flask" and wrote a book in 2001 about her research on the show called The Real Science Behind the X-Files: Microbes, Meteorites and Mutants.

What they don't talk about much is that the scientists weren't used to make things accurate, just plausible. For instance, the scientist consulted on "The Host" was ignored if she pointed out that a half-human/half-worm could never happen. She was only asked to come up with an idea for why it could happen.

8 THEY THOUGHT DUCHOVNY WAS STUPID

The role of Fox Mulder seems made for David Duchovny, who played the role with a twinkle in his eye and a deadpan delivery, but the road to X-Files wasn't always smooth. When his agent told him about the role in 1992, he wanted to act in movies and not television, but he hadn't gotten many roles. His agent had to talk him into auditioning for The X-Files.

The casting director thought Duchovny's audition was great, but Chris Carter thought Duchovny talked too slowly. In fact, Carter thought Duchovny was stupid. On the set after a few takes, Carter actually asked Duchovny to try imagining himself as an FBI agent in the future. In other words, try acting like the character they cast him as. Fortunately, Carter warmed up to Duchovny's style.

7 ANDERSON WASN'T SULTRY ENOUGH

While Duchovny had some movie and TV experience on his resume when he was cast as Fox Mulder, Gillian Anderson had very little TV experience before winning the role of Scully on The X-Files. That's the way she wanted it. Anderson has said she didn't really want to do TV shows since there was a stigma against television at the time that she shared. Her real dream was to be a movie star. Unfortunately, she wasn't getting any movie roles, so she reluctantly began auditioning for TV.

While Anderson ended up becoming one of the hottest sex symbols of the 1990s with her intelligence and beauty, the network wasn't sold on her. They wanted someone who was more of a blonde bombshell than the tiny redheaded actress Carter fought for. Carter won, and we're glad Anderson won them over.

6 SKINNER WAS TOO BALD

As the gruff and no-nonsense Assistant Director Walter Skinner, Mitch Pileggi shone throughout the X-Files series. He went from being Mulder's nemesis, wanting to shut down the X-Files division, to one of their only allies as the government fought against them. Just like the other roles, it's hard to imagine Skinner played by anyone else, but Pileggi almost didn't get the job because of his bald head.

No, we don't mean the baldness we're familiar with where he's bald on top and has hair on the sides. When Pileggi first tried to audition for X-Files, he had been completely shaving his head. According to Carter, that's why Pileggi was turned down for multiple auditions for different roles on the show. When he finally auditioned for the role of Skinner, Pileggi had let his hair grow out. The casting director finally saw him as the character we know and love.

5 THE SMOKING MAN WAS A CAMEO

If you wanted to point to anyone as the main bad guy on The X-Files, it was the one known as the Cigarette Smoking Man. The enigmatic man with the ever-present cigarette started out as a character in the background and grew in importance to become the arch-enemy of Mulder. He was a manipulative and brilliant character, always dominating the screen with a great performance by William B. Davis. One of the most surprising secrets behind the show is that the Smoking Man almost didn't exist at all.

In his first appearance, the Cigarette Smoking Man had no lines, just standing in the back of the office. That's how Chris Carter had intended the character, just as a cameo. Davis made such an impression, even without saying a word, that the show brought him back again and again until he became a major character.

4 THE NON-SMOKING MAN

If there's one thing that defines the Smoking Man, it's his cigarettes. In fact, he was almost never seen on the show without smoking one of his Morley cigarettes. In real life, the actor William B. Davis who played the Cigarette Smoking Man had a problem with the role. No, not having to be an evil and manipulative old man. Twenty years before he played the character, he had quit smoking for good in real life. Now he was required to smoke on the set, constantly.

In the first two episodes, he smoked real cigarettes, which triggered his craving for smoking again. Worried that he would fall back into the habit, Davis convinced the show to let him smoke herbal cigarettes, which tasted terrible, making it easier to put them down.

3 CRITICS HATED THE X-FILES

The X-Files is one of the most critically acclaimed TV shows in history. It redefined television itself by creating an anthology series that didn't feel like an anthology series, a running story arc that spanned multiple seasons and introduced many viewers to conspiracies and alien phenomena that are still being talked about today. That's why it's important to look back at how risky and poorly received it was when it first aired.

While there were critics who supported it, others flat out hated it. The Hollywood Reporter called it a "labored premise" and quipped that the "X" didn't mark the spot. The Washington Post said, "It's not quite sci-fi, not quite fantasy, and yet not quite realistic either. It's not quite a show, is what it's not quite." Even Entertainment Weekly called the show a "goner."

2 THE SHOW WITHOUT MULDER

Mulder and Scully were the heart and soul of the show, which is why fans panicked when Mulder was kidnapped by aliens in the seventh season finale. For most of the eighth season, Mulder was gone, seen only in brief visions where he was being tortured and analyzed by weird machines. His disappearance was actually caused by a fight behind the scenes.

In 1999, David Duchovny walked off the show over a contract dispute that almost ended with a $25 million lawsuit. Duchovny settled out of court, but part of his deal involved leaving the series as a regular cast member. It turned out that Chris Carter also worried that the show would be over without Mulder. However, he managed to come up with replacing Mulder with Special Agent Doggett.

1 X-FILES WITHOUT SCULLY AND MULDER

In the eighth season, Chris Carter and the Fox network had a problem: no stars. At the end of the seventh season, David Duchovny's contract ended and the star refused to return as a full-time cast member. The eighth season continued with Special Agent Doggett replacing Mulder, played by Robert Patrick.

In the ninth season, Mulder returned to Earth but went into hiding. Gillian Anderson's role as Dana Scully also scaled back as her character was reassigned to the FBI Academy. In her place, Agent Monica Reyes (played by Annabeth Gish) continued their hunt for the truth. Carter and the network hoped the new characters would catch on and keep the show going at least another two years, but the ratings plummeted. They finally had to accept The X-Files wasn't the same without Scully and Mulder and ended the series, at least until 2016.