It was written by series creator Chris Carter, directed by Paul Shapiro, and featured a guest appearance by Kathy Griffin.

"Fight Club" earned a Nielsen household rating of 6.9, being watched by 11.70 million people in its initial broadcast.

The show centers on FBI special agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) who work on cases linked to the paranormal, called X-Files.

"Fight Club" was inspired by a "long-lost nugget" of a story that series creator Chris Carter had thought up a while back about "mis-matched twins that had an almost nuclear reaction when they were around each other."

Steve Kiziak and Arlene Pileggi—David Duchovny's stunt double and Mitch Pileggi's wife, respectively—were chosen to play the Mulder and Scully look-alikes at the start of the episode.

Later, two FBI agents who look and sound remarkably similar to Mulder and Scully visit the first woman, Betty Templeton (Kathy Griffin).

Scully finds that the girls share the same father, a man by the name of Bob Damphouse, who is in prison and in a perpetual fit of rage due to insanity.

[2] Executive producer Frank Spotnitz concurred, noting that when he first looked at the script, he felt that "[the episode] had an odd tone.

Rick Millikan, the show's casting director, chose Randall "Tex" Cobb as Bert Zupanic and comedian Kathy Griffin as the doppelgangers.

He recalled, "I remember the director [Paul Shapiro], he wanted me to scream during rehearsal, and I was, like, 'Look, you don't understand: If I do this, I’m gonna have a headache in 30 fucking seconds.

"[2] The final scene, featuring a stadium full of people attacking each other after the Templetons make an appearance, was filmed at the Grand Olympic Auditorium in Los Angeles and made use of "several hundred" extras, many of whom were solicited via internet postings and ads that had been placed in "selected publications".

[2] Sixteen trained stuntmen and around 200 cardboard cutouts supplemented the hundreds of extras to give the stadium its final, filled-out feel.

When filming the crowd fight, producer Harry Bring later noted, "a few of [the audience] members got carried away and we had to tell them to settle down.

Club gave the episode a "D−"; he called it "dire stuff" and wrote that "there’s something rancid about forced quirk; it’s rotten and smug".

[9] Handlen both criticized Griffin's inability to portray two separate characters, as well as Carter's failure at writing a comedic script.

"[10] Christina Brzustoski from 11th Hour Magazine opined that "Just when you thought The X-Files couldn't get a more grating guest star than Victoria Jackson, Chris Carter manages to top himself yet again with not one, but two, for the love of God, two Kathy Griffins in the Carter-penned episode 'Fight Club.'

It's a safe bet this disjointed, lame episode will probably not be easily confused with the far superior David Fincher movie of the same name.

"[12] Robert Shearman and Lars Pearson, in their book Wanting to Believe: A Critical Guide to The X-Files, Millennium & The Lone Gunmen, rated the episode one star out of five.

Rich Rosell from DigitallyObsessed.com awarded the episode 4.5 out of 5 stars and noted that "There are some great visual moments in Fight Club, and Chris Carter reveals an almost Vince Gilligan-side to him with his comic writing here.