Mulder, Doggett, Walter Skinner (Mitch Pileggi), and Alex Krycek (Nicholas Lea) help Scully escape from Billy Miles with Special Agent Monica Reyes (Annabeth Gish) to a remote town.

Shortly after, Skinner kills Krycek and Scully delivers an apparently normal baby with the alien Super Soldiers surrounding her.

In Assistant Director Walter Skinner's office, a surveillance video shows Billy Miles leaving the morgue alive and well.

Doggett is called out of the office on behalf of his source Knowle Rohrer, who claims that Miles is part of a secret military project to create "super soldiers" and that Scully had a chip put in the back of her neck during her abduction to make her pregnant with the first organic version of a super soldier.

Monica Reyes helps Scully deliver an apparently normal baby, with the Super Soldiers witnessing the birth in a cold stare.

The night the episode aired, Lea wrote on his personal website: "I felt that [Krycek] wasn't getting a fair shake anyway.

Both Duchovny and Manners argued that the scene was "mundane" and that they had "been teasing and doing that bull for so long" that they wanted "a real kiss at this point".

Gish had never filmed with guns before joining The X-Files, so the producers hired a retired LAPD officer to teach her more about firearms.

Gish later noted that "[Series creator Chris Carter] gave me a tape of whale songs, which was hysterical to be playing in my trailer.

"[6] Carter was inspired to write the scene after a friend gave him a Paul Winter album that incorporated whale sounds into the music.

[10] In the United Kingdom, "Existence" premiered on June 28, 2001, and received 0.65 million viewers, placing The X-Files number three in the top ten broadcasts for Sky1 that week behind Star Trek: Voyager and The Simpsons.

While offering a positive opinion in regards to the finale as a whole, he felt that "Existence" dragged more so than "Essence", resulting in a less interesting episode.

He also felt that the overarching mythology of the series had long ago become too convoluted to make sense, but that the "human pieces of the show still work, and that includes Doggett.

"[14] Contra Costa Times columnists George Avalos and Michael Liedtke were pleased with the episode noting that the last scene was "beautifully written".

[15] Avalos and Liedtke also reacted positively to the death of Alex Krycek at the hands of Skinner, saying it was the best scene in the episode.

[15] Jessica Morgan of Television Without Pity gave the episode an A− rating, noting that "season eight's finale goes out with a big fat juicy kiss between Mulder and Scully, at long last".

Wigmore gave the episodes a 9 out of 10 rating and wrote "the reason that this two-parter works is that its plot is simple enough for the audience to still have a handle on".

Robert Shearman and Lars Pearson, in their book Wanting to Believe: A Critical Guide to The X-Files, Millennium & The Lone Gunmen, gave the episode a more mixed two-and-a-half stars out of five.

[19] She heavily derided the plot, and wrote, "Thus endeth the Mulder-and-Scully era of The X-Files, and what a load of sanctimonious crap it turned out to be!