Trivia: Scully's father, Scully's older brother, and the man Mulder thought was his biological father were both named William. (The father who raised Mulder went by "Bill, " as did Scully's brother.) Mulder's actual biological father, Cancer Man, was played by William B Davis (who also goes by "Bill"). Scully and Mulder's son was also named William (before being adopted and having his name changed to Jackson).
Trivia: The Cancer Man smokes Morley cigarettes, a fake brand that has appeared in a number of TV shows and movies since the '60s.
Trivia: In 2001, The Lone Gunmen were given their own self-titled TV series, The Lone Gunmen.
Trivia: Whenever the Cigarette Smoking Man smokes on the show, the actor is smoking herbal cigarettes.
Trivia: Two numbers that appear frequently during the series are 1013 and 1121. October 13 is series creator Chris Carter's birthday, and November 21 is his wife's birthday.
Trivia: The Lone Gunman is a reference to the Kennedy assassination, in which the Warren Commission reported that a lone gunman, Lee Harvey Oswald, killed President John F. Kennedy. Ironically, Bruce Harwood's character, John Byers, is named after Kennedy.
Trivia: Series creator Chris Carter changed the name of William B. Davis' character from "Cancer Man" to "Cigarette Smoking Man" about halfway through the series so tobacco companies wouldn't be offended. However, the character was still referred to by both names throughout the series.
Trivia: There was no character or characters who appeared in all 201 episodes of The X Files.
Trivia: Throughout the course of its initial nine-year run, The X-Files had crossovers with 3 other television shows: the short-lived Millennium in the season 7 episode "Millennium," COPS in the season 7 episode "X-COPS" and Homicide: Life on the Street in the season 5 episode "Unusual Suspects." The crossover with Homicide: Life on the Street is especially noteworthy as that show was produced by a different network. The X-Files also had a non-canon crossover with The Simpsons in their season 8 episode "The Springfield Files."
Trivia: The rock band Filter contributed music to this show, including their hit single "Hey Man Nice Shot" being used in the season 3 episode "D.P.O." as well as appearing on a couple X-Files soundtracks. Filter's lead singer Richard Patrick is the younger brother of Robert Patrick, who would later be cast in this show as Agent John Doggett.
Trivia: The echo effect in the series' theme tune was created purely by accident. Composer Mark Snow created the effect by resting his hand and arm on a keyboard which had an echo effect setting that had accidentally been turned on. Snow was so impressed with the riff that he wrote the theme around it.
Trivia: Rebecca Toolan plays David Duchovny's mother in the series, even though in real life she's only a year older than him.
Suggested correction: This entry is actually incorrect. There are records that prove she is much older than what's stated. By 1968, she married her first husband and was a university professor. Https://www.newspapers.com/clip/22109182/wedding-announcement-rebecca-cox-and/.
While there are many conflicting reports about Rebecca Toolan's age, it seems the Wikipedia entry is the most incorrect (which is where you got your source). It seems more probable than not that whoever edited her Wikipedia page linked a article about the wrong Rebecca Toolan.
