Trill was an inhabited planet. It was the homeworld of two sentient species who shared a symbiotic relationship: the Trill, a warp-capable humanoid species, and the Trill symbionts, who were non-humanoid. (DS9: "Invasive Procedures", "Equilibrium")

It is unclear if Trill was a member of the Federation. See: Talk: Trill.

Further information


In 2367, the USS Enterprise had to contact the Trill homeworld to send a replacement host for an injured ambassador. (TNG: "The Host")

In 2371, the USS Defiant traveled to Trill when Jadzia Dax's life was endangered by suppressed memories of her previous host, Joran Belar. (DS9: "Equilibrium")

In 2375, the USS Destiny was en route to Trill with the Dax symbiont, which had been injured, when the entity took a turn for the worse. As a result, it had to be joined with Ezri Tigan. (DS9: "Shadows and Symbols")


Trill had multiple oceans. They had a purple tint when viewed from space. (DS9: "Past Tense, Part I")

Points of interest

Institutions and agencies



Background information

In the series bible for Star Trek: Deep Space Nine, it was said that the underground of Trill and the planet's surface were where the Trill symbionts and humanoids lived, respectively. It was also stated that "an environmental disaster" led the two species to begin integrating with each other. [1]

As there were two make-up configurations designed for the Trill, Jadzia Dax actress Terry Farrell once suggested that "the north of Trill" was the birthplace of the simpler-looking Trill whereas the planet's south was where the more elaborate physical design, involving spots, originated. (Cinefantastique, Vol. 23, No. 6, p. 21) While filming DS9 Season 1 finale "In the Hands of the Prophets", Farrell also expressed hopes of seeing Trill in the second season of Star Trek: Deep Space Nine, saying, "I'd like to go to the planet where I'm from." (Cinefantastique, Vol. 24, Nos. 3/4, p. 98.)

The name of the Trill homeworld was first established as "Trill" in the third season outing "Equilibrium", which also marks the first time the planet appeared on Star Trek: Deep Space Nine. Portraying the planet in that episode proved highly expensive. Some of the Trill exteriors shown in "Equilibrium" were filmed on location in Huntington Gardens. "I think there were a lot of interesting things about the Trill homeworld that you found out in the episode," commented René Echevarria, who wrote "Equilibrium"'s script. (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, pp. 84 & 85.)


Worlds of Star Trek Deep Space Nine 2

Worlds of Star Trek: Deep Space Nine, Volume Two focuses on Trill and Bajor.

Star Trek: Star Charts (p. 33) and the Star Trek Encyclopedia (4th ed., vol. 2, p. 421) designate the Trill homeworld (Trillius Prime) as an M-class planet governed by the Trill Symbiosis, admitted into the Federation in 2285. The planet's capital was Mak'ala. Points of interest noted included the Hoobishan Baths, the Tenarian (Tenaran) Ice Cliffs, and the Caves of Mak'ala. As of 2370, the planet was populated by 650 million Trill and 11 million symbionts, though the existence of symbionts was not widely known prior to 2367.

According to Star Trek: Star Charts (pp. 36 & 46) and Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385"), the Trill system was located in the Alpha Quadrant. This was a binary system with a G-class star and a K-class star. The system was a destination on an Earth trade route in the 22nd century and on a major space lane in the late 24th century.

The Star Trek: Federation Travel Guide calls out local attractions including the Teneran Ice Cliffs (3/3 stars) in the southern hemisphere and the caves of Mak'ala (2/3 stars.) "The Interplanetary Bar and Grill" serving foods from hundreds of worlds is highlighted, noting "local cuisine failed to tempt our reviewers palate." The Selipsis is identified as Trill's largest and oldest beach resort. "Grow old in wisdom" is noted as a local key phrase to know.

Trill features heavily in the novels The Lives of Dax and Worlds of Star Trek: Deep Space Nine, Volume Two.

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