The first season of the science fiction and horror television series The X-Files commenced airing on the Fox network in the United States on September 10, 1993, and concluded on the same channel on May 13, 1994, after airing all 24 episodes.

The first season introduced main characters of the series, including Fox Mulder and Dana Scully who were portrayed by David Duchovny and Gillian Anderson, respectively, and recurring characters Deep Throat, Walter Skinner, and Cigarette Smoking Man. The season introduced the series' main concept, revolving around the investigation of paranormal or supernatural cases, known as X-Files, by the Federal Bureau of Investigation; it also began to lay the groundwork for the series' overarching mythology.

Initially influenced by Kolchak: The Night Stalker and The Twilight Zone, series creator Chris Carter pitched the idea for the series to Fox twice before it was accepted for production. The season saw the series quickly gaining popularity, with ratings rising steadily throughout its run; and garnered generally positive reviews from critics and the media. It helped to make stars of its two lead roles, and several of its taglines and catchphrases have since become cultural staples.

Although Carter initially conceived of the series based on the influence of Kolchak and The Twilight Zone, he has stated that the "leaping-off point" for the series' overall concept came from UFO lore. After being introduced to the works of John E. Mack—especially a study by Mack that reported that 3% of Americans claimed to have been abducted by aliens—Carter believed he had found his central theme. It was decided that the series would focus on the FBI to avoid something Carter had seen as a failing in Kolchak, whereby mysterious events would continually occur in one locale and be accidentally uncovered by the same character—by creating a fictional FBI unit which actively uncovered these paranormal cases, it was felt that the series would be "sustainable week after week without stretching the parameters of credibility". Early in the planning stages, Carter had envisioned that a significant proportion of the episodes would deal with investigations which uncovered hoaxes or cases which had been mistakenly viewed as paranormal. Although this decision never came to pass, the third-season episode "Jose Chung's From Outer Space" can be seen as a holdover from the idea.

The series revolves around its two main characters, which had been defined early in conception as the "believer" and the "skeptic". Of these, the "believer", Fox Mulder, was created with a character-defining personal motivation, involving the disappearance of his younger sister during his childhood, which he would believe to be a result of alien abduction. The creation of the "skeptic", Dana Scully, was influenced by Jodie Foster's portrayal of Clarice Starling in The Silence of the Lambs, leading the crew to decide that the character needed to seem "real", as opposed to the "bombshell" type of character the studio was pressing for.

Thematically, although the series focused heavily on alien abduction lore, the decision was made early on to allow the plots of individual episodes to branch out into different territories to prevent the overarching plot from running out of momentum, which led to standalone episodes such as "Squeeze" being developed. The variety of storylines which the series has shown has led director Daniel Sackheim to note that "The X-Files has found its own style in that it doesn't have a confined style to it", adding that the series' "fluid" approach has meant that "everybody who comes on the show attempt to make a little scary movie". To this end, several episodes feature varying plots, with alien-influenced storylines varying between "Ice", a "briskly-paced" episode set in one location, and the character-driven "Conduit", which served to fill in background on the characters. Elsewhere, plots focused on soul transference or reincarnation, with the episodes "Shadows", "Born Again" and "Lazarus" sharing similar storylines. The plot of "Ghost in the Machine" featured a malevolent AI; while "Shapes" introduced the first of what would become several Native American-themed episodes.

The first season also introduced many minor characters who would go on to become central figures to the series—The Lone Gunmen, first seen in "E.B.E.", would become regular characters beginning the second season, eventually starring in the spin-off series The Lone Gunmen; whilst the episode "Tooms" introduced Walter Skinner, portrayed by Mitch Pileggi, who would go on to be billed as a series star by the ninth season. The abduction of Mulder's sister Samantha was explored in the episodes "Pilot", "Conduit", and "Miracle Man", and would go on to become one of the central themes of the series as a whole.

California native Chris Carter was allowed to produce new shows for the Fox network in the early 1990s. Tired of the comedies he had been working on for Walt Disney Pictures, inspired by a report that aliens may have abducted 3.7 million Americans, and recalling memories of Watergate and the 1970s horror series Kolchak: The Night Stalker, Carter came up with the idea for The X-Files and wrote the pilot episode in 1992. He initially struggled over the untested concept—executives wanted a love interest for Scully—and casting. The network wanted either a more established or a "taller, leggier, blonder and breastier" actress for Scully than the 24-year-old Gillian Anderson, a theater veteran with minor film experience, who Carter felt was the only choice after auditions.