Dax actress Terry Farrell explains how the Trill changed on Star Trek: DS9 thanks to X-Men’s Jean Grey actress Famke Janssen’s guest spot on TNG.

The look of Star Trek‘s Trills changed on Star Trek: Deep Space Nine because of X-Men actress Famke Janssen, according to Terry Farrell, who played DS9‘s Lt. Commander Jadzia Dax. Trills are a symbiotic alien species that originated in Star Trek: The Next Generation season 4, episode 23, “The Host”, in which Dr. Beverly Crusher (Gates McFadden) falls in love with Trill ambassador Odan (Franc Luz), before Odan’s untimely death necessitates transferring the symbiote possessing his memories into a new host. Odan’s Trill makeup was typical of TNG‘s weekly aliens, with a prominent forehead piece designed by makeup legend Michael Westmore.

On The Delta Flyers podcast, beginning its coverage of Star Trek: Deep Space Nine after a long run focusing on Star Trek: Voyager, Farrell reveals to hosts Garrett Wang and Robert Duncan McNeill that Dax originally had a very different look, using the makeup design for the Trill that was on Star Trek: The Next Generation. The design was vetoed for Farrell, so Westmore substituted the spots used on the empathic metamorph Kamala from TNG season 5, episode 21 “The Perfect Mate.” Kamala was played by initial Dax pick Famke Janssen, who would reunite with TNG‘s Patrick Stewart in X-Men as Jean Grey. Read their quotes below.

Farrell: “The original makeup they tried to give me [was] the Trill makeup from the Next Generation. [When] the Trill was first seen [in “The Host”], he had quite a prominent forehead. And so they tried to do the same thing on me, and [producer] Kerry McCluggage called [and said] … no rubber on my head. … They wanted Famke Janssen to play Dax, and Michael Westmore took the spots from the character that Famke played on The Next Gen to put on me. I think they were a little different, but that’s where the inspiration came from.”

Wang: “Famke was a Trill on TNG?”

Farrell: “No, she was a different character.”

Wang: “A different alien.”

Farrell: “A different alien, but she had spots, and they thought those were sexy … we shot for a day, they saw the dailies, then said no, get rid of the forehead.”

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The TNG Trills Were Never Seen Again in Star Trek

When Star Trek: Deep Space Nine included Trill character Jadzia Dax as part of its main cast, the Trill were just one of many single-episode aliens encountered by the Enterprise in Star Trek: The Next Generation, but Trills evolved thanks to Dax on DS9. The new, spotted Trills blended the symbiont’s memories with the host’s to create a distinct individual, instead of the symbiont’s taking over like Odan’s did on TNG. The DS9-style Trills are the predominant ones in Star Trek, as new shows feature Trill characters like Gray Tal (Ian Alexander) on Star Trek: Discovery and the unjoined Ensign Barnes (Jessica McKenna) on Star Trek: Lower Decks.

On The Delta Flyers, Terry Farrell also explained that the makeup change further delayed an already tight filming schedule for Star Trek: Deep Space Nine‘s pilot episode, “Emissary.” Farrell was the last person cast among DS9‘s primary actors, and had to play catch-up as her scenes for the two-hour episode were compressed into roughly a week, after filming had already begun. After retooling the Trill makeup to resemble Famke Janssen’s spots, Farrell had to do another makeup test and then re-shoot the scenes that had already been completed. The delay was worth it, though, as the Trill spots have become iconic as a marker of this symbiotic species.