What is the iconic tagline of The X-Files?

The iconic tagline of The X-Files is "The truth is out there."

The phrase appears in the show’s opening title sequence and captures the series’ central premise: FBI agents investigate mysteries that official institutions cannot—or will not—explain. It is especially associated with Fox Mulder, whose search for evidence of extraterrestrial life and government secrecy drives the show’s mythology.

The tagline became closely linked with the 1990s science-fiction series and was used for most episodes. The opening sequence also featured eerie imagery, a glowing UFO-style silhouette, and the memorable X-Files theme by composer Mark Snow. Together, these elements helped establish the show’s distinctive atmosphere of paranoia and wonder.

Several related phrases are often mistaken for the main tagline. "I Want to Believe" is the slogan on the UFO poster in Mulder’s office, while "Trust No One" is another famous line associated with the series and appears as an alternate opening tagline in some episodes. The wording is normally capitalized as "The Truth Is Out There," but capitalization does not change the answer.