Star Trek: Lower Decks' Latest Season 5 Guest Star Has Lost His Head Before

This article contains spoilers for the latest episode of "Star Trek: Lower Decks."

"Star Trek" shows have been known to go big for their final seasons (or movie send-offs, as was the case with "Star Trek Generations"), and judging by this week's great episode, "Star Trek: Lower Decks" is no exception. The latest installment, "Fully Dilated," is one of my favorites of the entire series. It focuses on three great characters (Tawny Newsome's Mariner, Noël Wells' Tendi, and Gabrielle Ruiz's T'Lyn), utilizes one of the most impactful "Trek" tropes out there (time dilation), and includes a very silly-funny bit about Boimler and Rutherford spilling prawn cocktails all over the transporter panel during a particularly high-stakes moment.

"Fully Dilated" was already one of the more endearing episodes the reference-packed animated comedy has produced to date, but its positive qualities really went off the charts when it introduced its not-so-secret weapon: Brent Spiner's Data. More specifically, the Cerritos crew encountered the purple severed head of an alternate universe version of Data, who crash-landed onto the planet they ended up trapped on for a year. Spiner is still an active participant in the world of "Star Trek," having just appeared in "Picard" as recently as last year, but his warm presence is still incredibly welcome — and a big get for the final season of "Lower Decks."

The Cerritos team recovers Purple Data's head from the wreckage of an alternate Enterprise D, which comes from a place where everything seems to be exactly the same aside from its residents' love of the color purple. In an attempt to out-science T'Lyn and harness a promotion, Tendi reanimates the bifurcated android, keeping him in a lab of sorts where he doles out advice and tries to counterbalance Tendi's insecurities. At one point, she worries that Data needs a body, but he reassures her that he's been perfectly fine living as a severed head before.

Like many "Star Trek: Lower Decks" references, this throwaway line leaves more questions than answers for casual franchise fans who may not have seen the older "Trek" shows in a while. Or, rather, it begs one question in particular: when the hell was Data a severed head before?

To answer, we have to travel back to 1992, when "Star Trek: The Next Generation" ended its fifth season with an Emmy-winning, much-loved two-part episode, the second part of which actually aired as the season 6 premiere. Titled "Time's Arrow," the double-sized story sees Captain Picard (Patrick Stewart) and his team find evidence of alien visitation on Earth nearly 500 years earlier. That evidence? Data's severed head, which is found in a Bay Area cavern a mile underground, along with relics from the 19th century.

Soon enough, Data — the one with a body — ends up transported back to San Francisco circa 1893, allowing for the show to couple serious existential talks about the character's mortality with an entertainingly comical "What if we messed with history?" story arc. This "Doctor Who"-like interlude features appearances from Mark Twain and Jack London, plus plenty of fun, period-specific language and attire. The episodes also play around with time paradoxes, allowing the "Next Generation" crew to meet ship bartender Guinan (Whoopi Goldberg) in the 19th century because her future self told them to, and ultimately explaining Data's head with a trippy catch-22 of a climax.

Partway through the season 6 premiere, Data quite literally loses his head in a scuffle, and the ship's team brings his body back to the Enterprise of the future while in a time crunch. Luckily, Data's old head, found in the caves of California, is already on board the Enterprise, and Geordi (LeVar Burton) reattaches it to his present-timeline body. Picard, it turns out, encoded a secret message in Data's tooth back in the day, and when his head gets back to his body, he's suddenly given information that's vital to the mission.

We don't learn much about what Data's head was up to during its time on Earth, but time travel logic means that it was simultaneously trapped there for 500 years and wasn't separate from his body for very long. In contrast to the chatty, friendly Data of "Lower Decks," though, the head in "Time's Arrow" is creepy and vacant, clearly void of any life force or energy source. During the show's off-season, fans didn't know whether or not Spiner's character would end up killed off in the 19th century, as he suspected he would, and the mystery of his recovered head was only solved when the show came back three months after its cliffhanger finale.

Hilariously, "Lower Decks" doesn't just reference the other time that Data lost his head, but also jokes about the way "Time's Arrow" never really dealt with the realities of leaving Data's neural center behind on Earth. "Do not be so hard on yourself!" Data tells Tendi at one point when she's fed up with a science experiment. "I struggled to build an electromagnetic field core when I was trapped in 19th century San Francisco." When Tendi asks what Data did to overcome the obstacle, he reminded her that he couldn't do much as a decapitated head: "I waited in a cave until Captain Picard, myself, and some guy in a silver jumpsuit dug me out."

With respect to this frequently funny series, "Star Trek: Lower Decks" doesn't always make the most of its cameos, and it's great to see Data get plenty of screen time in this strong episode. He's also a strong scene partner for Tendi, whose Orion background makes her feel extra pressure to succeed in Starfleet. "I am the only android who has served on the Starfleet bridge, so I know how difficult it is to be the first," Data told Tendi during the closest thing the episode has to a sentimental moment. He also plays a major part in the show's plot, advising Captain Freeman (Dawnn Lewis) to allow Tendi and T'Lyn to work together as Science Officers. Our Lower Deckers are finally moving up in the world, with help from one of the best characters in "Trek" history.

New episodes of "Star Trek: Lower Decks" premiere each Thursday on Paramount+.