Star Trek Expanded Universe
See also: races and cultures and mirror universe


The Aenar were an Andorian ethnic subgroup with a history of enmity towards Andorians. In Star Trek: New Empire, they aided the Terran Empire's conquest of Andoria, hoping to gain advantage over the Andorians, to mixed results. They later aided the Terran rebellion, but again suffered at the hands of the second empire, which decimated most of the Aenar between late 2385 and early 2386, in response to the actions of Shran ch'Rothress. By 2386, the Aenar had been exiled from Andoria and driven to the brink of extinction. (Star Trek: New Empire)

In another timeline, the Aenar were a pacifist race who opposed the Empire's war with the Klingons and won over a large number of Vulcans. Earth exterminated the Aenar, leading Andorians to join the rebellion (partial conjectural mirror universe timeline).


A male Andorian

In 2155, an Andorian male crewmember, possibly a conscript, worked aboard the ISS Avenger at the helm. He was killed while aiding fellow non-Terrans under Soval in an attempt to destroy the USS Defiant. (ENT: "In a Mirror, Darkly, Part II")

Presumably, the Andorians were conquered by the Terran Empire. See also Untaken Treks.

In Star Trek: New Empire, after being freed from Terran Empire rule, Andoria became part of the Klingon-Cardassian Alliance. By the 2370s, however, Andorians resented the Alliance (Klingons in particular). Many supported and fought with the Terran rebellion against the Alliance, then joined the Imperial Union of Planets afterward. (Star Trek: New Empire)


Kira Nerys, a female Bajoran

The Bajorans were a race conquered by the Terran Empire. Bajor became a sovereign member of the Klingon-Cardassian Alliance following liberation by Alliance forces; some Bajorans, however, joined the Terran Rebellion (DS9: "Crossover", "The Emperor's New Cloak", et al.).

A Debt of Honor[]

Bajor's vedeks had sheltered many of the rebels on Terok Nor, often at great risk to their own lives.

Star Trek: New Empire[]

Bajor betrayed the Alliance and joined the Imperial Union of Planets.

Bait and Switch[]

Following the capture of Terok Nor by the Terran Rebellion, some Bajorans, including Kanril Eleya's parents, fled Bajor for Cardassian space. By 2410, the Cardassian Guard incorporated Bajoran personnel. (The Wrong Reflection)


The Bartokians were subjugated by the Imperial Union of Planets in 2385. (Star Trek: New Empire)


Betazoids once tried to use their abilities for personal gain in the Terran Empire, but because the Empire distrusted telepaths, met with stiff resistance. They joined the Alliance until the late 2370s. Foreseeing the Alliance's demise, they switched sides and joined the Imperial Union of Planets. Betazoid dissidents tried to engineer Betazed's secession from the IUP in 2385 but were unsuccessful. (Star Trek: New Empire)


The Bolians were heavily subjugated by the Terran Empire. In the late 24th century they joined the Imperial Union of Planets. (Star Trek: New Empire)


See: Borg (mirror).


Very little is known about the Breen of the mirror universe. Intendant Kira once told Benjamin Sisko that Breen icicles were warmer than Jennifer Sisko. (DS9: "Shattered Mirror")


Caitian in Star Trek IV: The Voyage Home (Federation universe)

Caitians served aboard Imperial starships of the late 24th century. (Star Trek: New Empire)

It was never clear whether they formally belonged to the Imperial Union of Planets.


The Calafans were a slave race to the Terran Empire under Empress Hoshi Sato. They were copper-colored as opposed to the silver-colored Calafans in the Prime universe, and were able to make Psionic contact between both universes. After 2157, High Priestess Yimar opened up a passage between the universes, using ionizing radiation on Point Abic at the amplifying dishes on Lafa II (In Between Days).


Elim Garak, a male Cardassian

The Cardassians were a founding race of the Klingon-Cardassian Alliance. (DS9: "Crossover", et al.)


Odo, a male Changeling

In the mirror universe the Bajoran wormhole remained undiscovered as late as 2375. Thus Changelings and other species native to the Gamma Quadrant remained unknown to peoples of the Alpha Quadrant, with the exception of Odo, who was killed on Terok Nor during a workers' revolt in 2370. (DS9: "Crossover")

Probably, Odo was, like his counterpart, one of "the hundred" and was found in the Denorios belt.


The Cygnians were once ruled by the Terran Empire, then later became a member race of the Imperial Union of Planets. Several served in the Imperial Starfleet. (Star Trek: New Empire)

This race was identified as the lavender-skinned species seen in "Journey To Babel" (TOS), although canon does not confirm this.


Phlox, a male Denobulan

Denobulans were a slave race of the Terran Empire. Phlox served aboard the ISS Enterprise as ship's doctor. Denobulans were not part of the rebellion against the Empire, as it was not in their nature. (ENT: "In a Mirror, Darkly, Part II")


Quark, a male Ferengi

The Ferengi were, for the most part, seen as far more compassionate and less greedy than their counterparts in the "primary" universe, often paying for this compassion with their lives. The Terran Empire ravaged their homeworld in the 23rd century (Star Trek: New Empire), while in A Debt of Honor Ferengi dilithium shipments helped the Alliance defeat the Empire. The Alliance oppressed them during the 2370s and some Ferengi were members of the rebellion. (DS9: "Crossover", et al.)


Slar, a male Gorn

A Gorn named Slar was a slave master working for the Tholian Assembly. He was in charge of the workers assigned aboard the USS Defiant until the crew of the ISS Enterprise took it over. Slar was seen as untrustworthy of humans and vicious when it came to dealing with them. He was ultimately killed by Jonathan Archer. (ENT: "In a Mirror, Darkly, Part II")

Some Gorn worked in various capacities both in and out of Starfleet in the late 24th century. See: Sselraan, Ssslon. (Star Trek: New Empire)


Tharn, a male Halkan

Like their counterparts (TOS: "Mirror, Mirror"), the Halkans were a peaceful race, avoiding violence at all costs. In "A Debt of Honor" their pacifism became a role model for Spock's reform efforts, but it led to Spock's being overthrown by the Imperial Starfleet.

This appeared to be one of the rare examples of races being virtually identical in both universes.


The Hydrans of the Mirror Universe were constituted in a Hydran Republic and indulged in brash partying in their universities, and were at war against the Lyrans (as opposed to the Hydrans of the prime universe, who fought the Kzinti alongside the Lyrans) (RIS Bouteina: "Party School")


One of the Iroids, Imirissen, served on board the ISS Imperia in 2386. (Star Trek: New Empire)


Worf, a male Klingon

The Klingons were a founding race of the Klingon-Cardassian Alliance. (DS9: "Crossover", et al.)

In Star Trek: New Empire, the Klingons were virtually wiped out by 2386, robbed of political and military power after years of siege by the Imperial Union of Planets. Klingon resistance cells continued to operate, however, often in collusion with Romulans. (Star Trek: New Empire)


The Kzinti fired on a Vulcan ship that visited Earth to find out what had happened to their survey ship two years earlier, forcing humans and Vulcans to become uneasy allies. Vulcan's subsequent war with the Andorians allowed Earth to come out from under Vulcan's shadow (partial conjectural mirror universe timeline).


The Lokirrim are a distant species from possibly the Delta Quadrant. Some of them have traveled to the Alpha Quadrant by the end of the Terran Rebellion. They are a relatively neutral species, having no political position due to the fact they come from so far away. The most use the Lokirrim are to others are as targets for pirates and looters.

In 2382, Aeon Ryku stole a Lokirrim vessel, the Chimera, from Pelios Station and converted it to his own use in the Terran Empire's Starfleet as the ISS Descent. (Star Trek: Shattered Universe: "Rising Empire")


The Naish were known for their love of wealth and splendor. A Naish dilettante visited Risa in 2385. (Star Trek: New Empire)


A female Orion

An Orion female crewmember, possibly a conscript, worked aboard the ISS Avenger. She was killed while aiding fellow non-Terrans under Soval in an attempt to destroy the USS Defiant. (ENT: "In a Mirror, Darkly, Part II")

It is not stated but implied that the Terran Empire annexed the Orions by 2155. Another theory is that the Orion Syndicate were allies. Either way, the Empire presumably discovered some sort of protection against the Orion females' pheromones, or they lack the pheromones in the mirror universe.

In the late 24th century, Orions commonly served in Starfleet, while others led lives as pirates. (Star Trek: New Empire)

In Star Trek: New Empire, the Empire indeed suppressed Orion females' pheromones, via prescribed medical injections. This was a requirement of all Orion females in Starfleet service.
In another timeline Vulcans attempted to use mind-melds to control the Orion women, but this had the unexpected effect of suppressing their ability to give off these pheromones (partial conjectural mirror universe timeline).


The Remans served as soldiers in the Romulan Technocracy, to which they supplied Reman warbirds. Their status following the fall of Romulus to the Empire remains unrevealed. (Star Trek: New Empire)

In Star Trek: New Empire, Remans were classified as genetically engineered offshoots of the Romulans.

Richtor's species[]

A member of this unnamed humanoid species, known for black spiral-shaped pupils, served aboard the ISS Arcadia in 2385. (Star Trek: New Empire)


Captain Valaris

During the 23rd century the Romulan Republic had a series of outposts along their border with the Terran Empire. They are known for being ruthless to their enemies but helpful and polite to friends and allies. (Star Trek: Eagle)

The Romulans appeared to be uninvolved in the conflict between the Terran rebellion and the Klingon-Cardassian Alliance. The primary Benjamin Sisko, portraying his mirror counterpart, indicated to Jennifer Sisko that he would visit the Romulans in an attempt to gain their support. This was, in actuality, a ruse to explain his return to Deep Space 9. (DS9: "Through the Looking Glass")

In Star Trek: New Empire, the Romulan Technocracy became the governing regime of the Romulans as the result of a disastrous clash with the Terran Empire. By 2386 Romulus had joined the Imperial Union of Planets. (Star Trek: New Empire)


The ISS Enterprise had contact with the Suliban by January 2155, acquiring a cloaking device from this species. (ENT: "In a Mirror, Darkly")

The circumstances of the encounter went unrevealed.


Terev, a male Tellarite

The Tellarites were apparently conquered by the Terran Empire sometime before 2155 and some had joined the rebellion against the Empire. Malcolm Reed and Phlox tortured a Tellarite crewman named Terev in the agony booth as a demonstration of the device for ISS Enterprise captain Maximilian Forrest and Commander Jonathan Archer. (ENT: "In a Mirror, Darkly")

In Star Trek: New Empire, the Tellarites later joined the Imperial Union of Planets.


Jonathan Archer, a male Terran

In the mirror universe, humans were filled with fear and suspicion when a Vulcan scout ship landed on Earth to initiate first contact. The humans slaughtered the Vulcan crew and used the technology within to create an interstellar empire. This Terran Empire lasted almost three centuries until it was overshadowed by the equally vicious aspirations of Klingons, Cardassians, and Bajorans. Although many races in the mirror universe harbored hopes of forming a peaceful alliance to protect civilization, Terrans were rarely found among these rebels due to the wealth and safety afforded by their violent expansionist policies.


A Tholian

There appeared to be no open hostilities between the Terran Empire and the Tholians in 2155, though the Tholians were known to annex systems close to their space. A single Tholian starship was no match for an NX-class vessel like the ISS Enterprise though several of these vessels were capable of destroying such a vessel, particularly when employing a Tholian web. (ENT: "In a Mirror, Darkly")

It's unclear what the long-term consequences were for a Terran Empire ship invading Tholian space, stealing the Defiant, and destroying several of their ships.


Jadzia, a female Trill

It is unclear which side (if any) the Trill government took in the conflict between the Alliance and the rebellion. A number of individual Trills, such as Jadzia, joined the rebellion, while others such as Ezri Tigan sought to remain non-aligned. (DS9: "Through the Looking Glass", et al.)

In Star Trek: New Empire, Trill symbionts were not revered but seen as parasites, under the belief that "joining" was a form of mind control. A war early in their history eradicated most of the symbionts. By 2385 the planet Trill had joined the Imperial Union of Planets. (Star Trek: New Empire)


Soval, a male Vulcan

In 2063, when the Vulcans made first contact with Earth, Zefram Cochrane shot the first Vulcan to set foot on Terran soil. The Terrans stormed the T'Plana-Hath and studied Vulcan technology. Eventually, the Terran Empire was able to conquer the Vulcans. (ENT: "In a Mirror, Darkly")

By the 2150s, Vulcans were considered slaves to Terrans and not treated as equals. A number of Vulcans and Vulcan ships rebelled against the Terran Empire. By 2267, their attempts seemed to have been unsuccessful, although it appeared that Vulcans such as Spock were treated with more respect and feared by some Terrans. (ENT: "In a Mirror, Darkly, Part II", TOS: "Mirror, Mirror")

In the 2370s, Vulcans served as slaves to the Klingon-Cardassian Alliance. Several were seen fanning the Intendant on Terok Nor. (DS9: "Crossover") Some Vulcans, such as Tuvok, joined the Terran rebellion. (DS9: "Through the Looking Glass")

Jonathan Archer mentioned humans turning the tables on the Vulcans' invasion force. This might have been an assumption based on Archer's paranoia (or government propaganda).

In Star Trek: New Empire, Spock's reforms, which became known as "Spock's folly", led to the destruction of the Terran Empire and the enslavement of humans, earning Vulcans a negative social stigma. Although many supported and fought with the Terran rebellion, they were widely regarded with loathing and suspicion in the Imperial Union of Planets, which they joined purely to avoid destruction at the "new Empire"'s hands. In this continuity, the Alliance ravaged Vulcan much as it had Earth, albeit not quite as badly. (Star Trek: New Empire)


The Xindi fought in a conflict with the Terran Empire sometime prior to 2155. (ENT: "In a Mirror, Darkly, Part I" & ENT: "In a Mirror, Darkly, Part II")

Seen in the opening credits for those episodes.

Empress Hoshi Sato committed genocide on the Xindi people, sometime before 2157, with fewer than 1,000 left of any species (In Between Days: Reversal).

Mirror universe cultures article at Memory Alpha, the canon Star Trek wiki.