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In the “Star Trek: Lower Decks” episode “Crisis Point,” which we rank as one of the five best of the show, Ensign Boimler (Jack Quaid) has written a specialized holodeck program for himself wherein he’ll be able to interact with holographic versions of his superior officers. Boimler aims to act more naturally and confidently in front of his commanders, hoping it will make him a better officer. Ensign Mariner (Tawny Newsome), however, sees Boimler’s program and immediately wants to mess with it. She breaks into Boimler’s program and almost instantly reprograms it into a “movie,” wherein she’ll interact with the crew of the U.S.S. Cerritos in a more dramatic — and violent — fashion. It should be noted that Mariner’s mother is the captain of the Cerritos, meaning she’s about to enact some very unhealthy fantasies.

As the opening credits for Mariner’s “movie” begin rolling, Boimler whines that he doesn’t want to take part in whatever Mariner just invented. “I don’t want to do a movie!” he wails. Mariner replies with, “That’s okay. You were kind of a Xon, to be honest. You probably weren’t going to make the final cut.” Boimler is confused. “Who’s Xon?,” he asks. “Exactly,” Mariner says. 

Like many throwaway gags in “Lower Decks,” the passing reference to Xon is a deep-cut piece of Trek trivia only the most devoted Trekkies might know. Xon, very briefly, is a character from the unmade “Star Trek” TV series “Star Trek: Phase II,” a series that was put into production in the late 1970s, but never actually released. A lot of “Phase II” was repurposed to make “Star Trek: The Motion Picture” in 1979. The character of Xon was to be the show’s central Vulcan character, played by actor David Gautreaux. “Lower Decks” just made him (kinda sorta) official. 

/Film has written about “Star Trek: Phase II” before, and its making (and unmaking) is common knowledge to a lot of Trekkies. For those who want to do more reading, a lot of the story of the making of “Phase II” was laid out in Garfield and Judith Reeves-Stevens 1997 book “The Continuing Mission.” 

To catch up any newbies and “Star Trek” neophytes, “Star Trek: Phase II” was put into production in 1977, way back when Paramount wanted to launch its own network. At the time, there was some drama between Spock actor Leonard Nimoy and show creator Gene Roddenberry, however, leading to Nimoy’s refusal to take part. Because his Vulcan character was so popular, however, Roddenberry and the “Phase II” showrunners decided to create a new Vulcan character to “replace” him. 

The new character was Xon. Resourceful internet hunters can likely find photos online of actor David Gautreaux in the Xon makeup. He was younger than Spock, and was said to be going on his first mission. He was a full-blooded Vulcan, and had little insight into the human world. 

Several scripts for “Phase II” were written, and the new series was also to feature characters named Ilia (a bald, libidinous Deltan) and Will Decker. Those characters were eventually used as central figures in “Star Trek: The Motion Picture.” It seems that as “Phase II” was being developed, Paramount began to find that making a “Star Trek” movie might actually be a smarter move than investing in a new TV series, and the Ilia and Decker characters were shunted over into that project. Xon, however, was abandoned, as Nimoy eventually changed his mind, got over the bad blood, and agreed to return as Spock.

When Spock returned, Xon was written out. This explained Mariner’s statement to Boimler about how he was “kind of a Xon” and wasn’t going to make the final cut. Mariner was making her own “Star Trek” movie inside an episode of “Star Trek,” and already postulated that some of her characters would be lost in development (never mind that her movie was almost instantly completed and required no development). 

This is, of course, a meta joke about the production process of a movie, and not an explicit reference to anything that happened inside the “Star Trek” universe proper. But because we Trekkies are sticklers for continuity, it also means that Xon, in being mentioned explicitly in dialogue, is now officially part of the “Star Trek” canon. Xon was real in “Star Trek” history now, even if he had never technically appeared on screen before. What is Xon’s personal history? We don’t know. Mariner’s comment only stated that he exists. Trekkies can now theorize that he was indeed a member of the crew of the U.S.S. Enterprise shortly before the events of “Star Trek: The Motion Picture,” but that he left or was simply busy during the movie. 

Some Trekkies have noted that a character named Xon had a background office in “Star Trek II: The Wrath of Khan,” and that he was a captain (but this was only seen in notes on the film’s set decoration, which isn’t easily accessed). Xon also turned up in a series of 1984 comic books called “Saavik’s Story,” although “Star Trek” comics — while a wide and important part of “Star Trek” fandom — are 100% not canonical. It wasn’t until “Crisis Point” that Xon actually entered the central myth of “Star Trek.”