Introduced in the series' second episode, also named "Deep Throat", the character was killed off during the first season finale "The Erlenmeyer Flask"; however, he later made several appearances in flashbacks and visions.

[6] Hardin believed his initial appearance would be a one-time role, although he soon found himself regularly commuting to the series' Vancouver filming location on short notice.

Deep Throat felt that the truth the Syndicate kept secret from the public needed to be known, and believed Mulder to be the one person capable of exposing this knowledge.

When a UFO was shot down over Hanoi by US Marines, the surviving extraterrestrial was brought to Deep Throat, who executed it (depicted in flashback for the fourth season episode "Musings of a Cigarette Smoking Man").

[12] In the first season finale of The X-Files, "The Erlenmeyer Flask", Mulder was taken hostage by a group of Men in Black operatives, following his investigation into an alien-human hybrid program.

Entertainment Weekly described Hardin's performance as "world-weary and heavyhearted",[21] and listed his appearance in the character's eponymous début episode as the 37th greatest television moment of the 1990s.

Club, Zack Handlen called Deep Throat's death "a shocking moment, even when you know it's coming", praising the "desperation" evident in Hardin's performance, although lamenting the "curse of continuity" that led to the character being quickly replaced with Steven Williams' X.

[26] Ben Rawson-Jones, writing for Digital Spy, felt that Deep Throat's tenure on The X-Files was "arguably the show's peak", and praised Hardin's acting in the role.

[27] Brian Lowry, in his book The Truth Is Out There, has noted that the character "helped establish a tone and undercurrent of gravity on The X-Files that was to provide the spine of the series".