Aenar government has little structure; leaders of Aenar society are chosen as the need arises, usually when contact with outsiders is called for. The Aenar are generally considered just a different ethnicity of the Andorian race and not a separate species.

The Aenar population is about 11,000 in size, and they inhabit the polar region of their world. Andorians believed the Aenar to be mythical creatures before their existence was confirmed circa 2104.

Based on Talla, Shran's daughter from "These Are the Voyages..." (ENT), it has been speculated that mixed-race individuals of Andorian and Aenar origin would be a greenish color, perhaps explaining the greenish Andorian seen in Star Trek: The Next Generation.^{[citation needed]}

In Star Trek: Strange New Worlds, Hemmer, the chief engineer of the USS Enterprise, is an Aenar. He dismisses any claims that his blindness is a handicap, claiming his telepathy more than compensates for it.^[2]

Andorians are a humanoid species with blue skin and antennae. They consider themselves a warrior race, contrasting with the pacifist Aenar. They are native to the moon Andoria, which orbits the planet Andor. They were a founding member of the United Federation of Planets.

The Antedean race is divided over whether membership in the Federation is good. Ambassador Lwaxana Troi foiled a plot on Stardate 42859.2 when two Antedeans tried to sabotage their planet's Federation membership conference on Pacifica with ultritium concealed in their garments.

Nothing has been revealed about them in dialogue, so their backstory (by Fred Phillips and Robert Fletcher) is considered semi-canon.

One of James T. Kirk's earliest commendations is the Palm Leaf of Axanar Peace Mission, following the Battle of Axanar; However, the exact nature of the conflict is unrevealed; it is revealed in the episode "Whom Gods Destroy" that Starfleet Captain Garth of Izar achieved a great victory on behalf of the Federation, and his strategies became required reading at Starfleet Academy (since Kirk himself studied these strategies, the Battle of Axanar must thus have occurred well before Kirk entered Starfleet Academy in 2250, which was itself almost 20 years before "Whom Gods Destroy"). Kirk claims that the Axanar Peace Mission "topped [Garth's victory] with a greater one" and preserved the civilization that made Spock and himself "brothers," implying that the mission may have contributed to healing a severe rift in the Federation at that time.

The Bajorans are a humanoid species with characteristic nose creases. They live on the planet Bajor. They are deeply spiritual people who worship The Prophets. They are enemies of the Cardassians, who occupied Bajor and treated the Bajorans as enslaved in the early 24th century. Time Magazine called the Bajorans "a proud people struggling to recover from another species's hostile occupation of their world."^[1]

The Ba'ku people were a technologically advanced humanoid civilization. In the early 21st century, the race developed the means of building weapons of mass destruction and was on the brink of self-annihilation. A small enlightened group of the Ba'ku people escaped this horror and found an isolated planet.

This group of Ba'ku followed a simple way of life and disdained the use of technology. (As shown in the film Star Trek: Insurrection, however, the Ba'ku still possessed some form of technology and the ability to use it in emergencies since they had attempted to repair the damaged Data.) At first, the Ba'ku were unaware of the metaphasic radiation in the planet's rings, which caused their aging process to decelerate significantly, although it was later discovered and cherished.

The Ba'ku society consisted of strong bonds between individuals, as fewer than a thousand lived in a village. Their more straightforward way of life eventually prompted some of the younger Ba'ku villagers – who wanted to explore the galaxy with off-landers – to rebel against their elders, and an attempt was made to take over the village. When they were unsuccessful, they were exiled and eventually became the Son'a people.

In 2375, peace on the Ba'ku planet was restored, and several members of the Son'a returned to their families.

Perhaps purely by coincidence, "Bandi" was the name of a vaguely ursine empathic parasite in an early Star Trek story premise by David Gerrold, who was involved in the development of Star Trek: The Next Generation and novelized "Encounter at Farpoint."

Benzites possess smooth, hairless skin; they may range in color from bluish-purple to green-blue. A thick protrusion of the Benzite skull extends down over the face, displaying a prominent nasal lobe and brow. Two fish-like barbels droop down from above the upper lip. Benzites are highly resistant to poisons and other harmful substances. They can digest and derive nutrition from almost any organic compound. All Benzites from the same geostructure are physically similar, so much so that they are indistinguishable from a non-Benzite.

Customs: The word Imzadi, meaning 'Beloved,' is often used between a Betazoid and their partner, whether they are of the same species or not. Betazoid weddings are conducted with the bride, groom, and several participants completely naked. The newlyweds possibly remain so for the duration of the honeymoon (TNG episode "Haven," novel The Persistence of Memory). A Betazoid woman's sex drive quadruples (at the least) when she reaches a certain age (TNG episode "Manhunt").

The Bolian world has been an active member of the Federation since 2320. Aside from contributing to the ranks of Starfleet, they have a delegation within the Diplomatic Corps. In 2366, the Bolian government was maintaining an uneasy truce with the Moropa (TNG: "Allegiance").

The Bolians are known to make crystal steel that is highly prized. They also own and operate the famous Bank of Bolius. In 2373, the Bolian government authorized the Ferengi Gaming Commission to manage their gambling emporiums.

During the Bolian Middle Ages, the Bolians developed the medical philosophy known as the "Double Effect Principle" about euthanasia. This form of assisted suicide states that while euthanasia has the effect of relieving suffering, it also has the effect of causing death. Bolian marriages often involve more than two members. Any additional spouse is referred to as a "co-husband" or "co-wife." Bolian blues is a highly appreciated musical genre among Federation species.

(TNG)
"Scorpion" (VOY)
"Unimatrix Zero" (VOY) "Endgame" (VOY)
"Regeneration" (ENT)
Star Trek: First Contact

While encountered in the Enterprise episode "Regeneration," the Borg, a pseudo-species of cybernetically enhanced individuals, were not fully identified as the single greatest threat to the Federation until the events of The Next Generation episode "Q Who?". The Borg were discovered to be a group without individuality, where every member is a part of a collective consciousness in an attempt to achieve perfection. They assimilate any species they come into contact with for either biological aspects (for example, Talaxians would be incorporated for their dense physical structure, helpful in producing solid and resilient drones) or technological aspects (a species that has developed advanced engines or weaponry would be a sufficiently desirable target for assimilation) all in an attempt to improve further the overall perfection of the Borg as a whole.

The Borg have encountered and assimilated thousands of species, quantity most notable by their designation of Species 8472, although more may have been added to the total since that encounter.

The Borg are not a species but a collection of species. In their assimilated state, most races are altered or augmented with cybernetic enhancements that make them all look similar or instantly identifiable as Borg, making them a pseudo-species.

Encounters with the Borg have varied in type, from the disastrous defense of the Wolf 359 system ("The Best of Both Worlds"), in which many Federation ships were lost, the successful repelling of two Borg cubes from Sector 001 on two separate occasions ("The Best of Both Worlds" "Star Trek: First Contact") and the infiltration, usage of and destruction of a Borg transwarp hub (a critical part of their interstellar menace) by the USS Voyager ("Endgame").

The Breen are a mysterious race who joined the Dominion during the Dominion War.

The Cardassians are enemies of the United Federation of Planets and are mentioned in Star Trek: Deep Space Nine, Star Trek: The Next Generation, and Star Trek: Voyager. They have noticeable ridges along their foreheads and necks and a crest on their foreheads, earning them the nickname, Spoonheads. Their government is a military dictatorship.

Production design: Their makeup design was done by Michael Westmore, and their costumes by Robert Blackman.^[5][6]

Major Cardassian characters: Garak, Gul Dukat.^[7]

According to Time Magazine, Captain Picard found the Douwd he met an alien "being of extraordinary power and conscience" and felt they should be left alone.^[1]

El-Aurians appear outwardly identical to humans and have a variety of ethnic types, with both dark- and light-skinned members of the race being shown in various Star Trek movies and television episodes. They can live well over 700 years. They are considered a race of listeners and often appear patient and wise.

El-Auria, the El-Aurian homeworld, was located in the Delta Quadrant and was destroyed by the Borg in the mid-23rd century. Few survived, and those who did were scattered throughout the galaxy. Some of the refugees came to the United Federation of Planets.^[11]

At the start of Star Trek: The Next Generation, the Ferengi are considered a mysterious race who care only about profit. They feature as major characters in Deep Space Nine.^[1]

One of the noted Ferengi is Quark. The race is known for its Rules of Acquisition, sacred precepts that they try to live by.^[1]

Kirk fights with this lizard-like alien in the 1967 "Arena" episode of the original Star Trek series.^[8]

Several Gorn ships attack the Enterprise while under Captain Pike's command (SNW).^[12]

In 2017, Den of Geek ranked Gorn the 23rd best alien species of the Star Trek franchise.^[13]

Reception

In 2017, ScreenRant ranked the Hirogen the 10th most bizarre aliens in the Star Trek franchise up to that time.^[8]

Every 50,000 years, the entire species die off, except for one mother, who lays thousands of eggs and protects them from danger.^[8] In that episode, the creature clashes with a mining colony due to a misunderstanding.^[15]

"Ghosts of Illyria" (SNW) "Ad Astra per Aspera" (SNW)

Conceived as "more than just another fearsome alien", the Deep Space Nine makeup department searched for concepts depicting "toughness and resiliency" in the design of the Jem'Hadar. The final design was based on a rhinoceros, with some added ceratopian traits. Originally designed on the premise that they were all clones, the first Jem'Hadar seen onscreen were all made to look identical to one another. However, as they became more deeply woven into the storylines, each Jem'Hadar was given a distinctive look.^[19]

In 2017, ScreenRant ranked the Jem'Hadar as the 7th most bizarre aliens in Star Trek.^[8]

In 2017, Den of Geek ranked the Jem'Hadar the 11th best aliens of the Star Trek franchise.^[13]

The Kazon aliens were introduced on Star Trek: Voyager.

The Klingons are a warrior race with a strict honor code. Their popularity is strong for a fictional race, and they had real language written for them that is spoken in the real world, unique among science fiction aliens.^[15]

Although the Klingons look very human-like in the original series, they underwent a design change for The Next Generation, explained in the show as a massive genetic alteration that added the iconic ridged foreheads.^[20]

The Kzinti are feline warriors that appear in the TAS episode The Slaver Weapon, who originated in Larry Niven's Known Space universe. The Kzinti had four wars with humanity. According to Sulu, the last one was 200 years before their appearance in the episode. In the STP episode Nepenthe, Riker says that Kzinti are present on the titular planet.^[21]

The Lanthanites were introduced in the person of Chief Engineer Pelia in the first episode of the second season of Star Trek: Strange New Worlds. Long-lived, they are noted for having surreptitiously been present, unnoticed, on Earth until the 22nd-century. They serve at Star Fleet Academy and in the fleet.^[22]

The Organians were a race of beings who had evolved into pure conceptual beings, the essence of thought with no human bodies. In some ways, they were similar to Q for power levels and abilities. In the novel Q Strike, the Organians appear to observe a battle between members of the Q Continuum and other seemingly omnipotent beings from the Star Trek universe. The original Q identifies them after being asked by Captain Jean-Luc Picard who they are and is rather dismissive, remarking that "compared to their code of noninvolvement, your Prime Directive is practically an incitement to riot."

The Organians also appeared on Star Trek: Enterprise in the episode "Observer Effect," where they observed members of the crew infected with a silicon-based virus to decide whether or not they should make first contact with humans. They did not technically appear onscreen; they only manifested themselves by possessing the bodies of several members of the Enterprise crew.

In 2017, Den of Geek ranked Organians the 20th best aliens of the Star Trek franchise.^[13] In 2020, ScreenRant ranked them the 5th smartest aliens of the Star Trek franchise.^[23]

Orions are a green-skinned, humanoid alien species in the Star Trek universe. An Orion was first portrayed as an illusion in the original Star Trek pilot. She was seen as well in the broadcast series when this original pilot was incorporated into a two-part episode (episodes 11 and 12) in the first season. Orions are also portrayed in Star Trek: The Animated Series, Star Trek: Deep Space Nine, Star Trek: Voyager, Star Trek: Discovery, Star Trek: Enterprise, and Star Trek: Lower Decks. Rachel Nichols played Orion Starfleet cadet Gaila in the 2009 Star Trek film.

Romulans are humanoid extraterrestrials that appear in the Star Trek television series, where members of their race often serve as antagonists. They are a violent, treacherous offshoot of the Vulcans and rule the militaristic Romulan Empire.

They prominently feature in the film Star Trek: Nemesis.

Once members of the neo-luddite race the Ba'ku, the Son'a were exiled from their home planet by their fellows for trying to overthrow the leadership and embracing more advanced technology. Now separated from the rejuvenating properties of the Ba'ku planet, they attempt to avoid death through medical procedures. The Son'a use of technology, including weaponry, was banned within the Federation. Nonetheless, in 2375 the Federation allied with the Son'a to take advantage of their technology to gather rejuvenating 'metaphasic particles' emanating from the rings of the Ba'ku planet, which is in Federation space. After the operation, which involved the forced relocation or genocide of the Ba'ku, was called into question and stopped by the crew of the Enterprise, a number of the Son'a reintegrated into the Ba'ku population. Others later joined the Dominion. The Son'a have subjugated two peoples as their slaves: the Ellora and the Tarlac.^[24]

Species 8472 appeared in four episodes of Star Trek: Voyager.^[25] While passing through Borg space, Voyager encounters Species 8472, a race that surpasses the Borg in combat prowess.^[26]

In 2017, Den of Geek ranked Talaxians the 21st best aliens of the Star Trek franchise.^[13]

They are a race that used to be technologically advanced and warp-capable, but a nuclear holocaust devastated their homeworld.

The Talosians are noted for their power of illusions.

In 2017, Den of Geek ranked Talosians the 16th best aliens of the Star Trek franchise.^[13]

Tellarites did not appear in the TNG-era shows, but on Enterprise they are a significant part of several episodes, becoming one of the founding species of the United Federation of Planets.^[27][28] They also appear in Discovery, in which Gorch, a Tellarite Starfleet admiral, is depicted.^[29][30] The animated series Lower Decks depicted a Tellarite captain in the episode "Moist Vessel."^[31] In the animated series Prodigy one of the main characters, Jankom Pog, is a 16-year-old Tellarite.^[32]

In 2017, Den of Geek ranked Tellarites the 25th best aliens of the Star Trek franchise.^[13]

Tribbles are a small, harmless species noted primarily for their ability to reproduce extremely quickly; this rapid reproduction creates massive Tribble colonies which can be dangerous to any ecosystem.

The Trill made their debut on television in the Star Trek: The Next Generation episode "The Host" (May 11, 1991), and were further developed in Star Trek: Deep Space Nine. The Trill Jadzia Dax is the 8th host of the symbiont Dax, and together they are one of the main characters of Deep Space Nine for the first six seasons; when Jadzia is killed, Ezri Dax, becomes the next Dax host for the seventh and final season. This species was also briefly represented as a holonovel character corresponding to Ensign Harry Kim on Star Trek: Voyager in "Author, Author" (April 18, 2001).

Adira Tal, a human joined with a Trill symbiont, appears in the third season of Star Trek: Discovery.^[33] A Trill doctor, Naáshala Kunamadéstifee, appears in Star Trek: Picard,^[34] and several Trill also feature in Lower Decks.^[35][36]

Trill have been studied in analyzing the biology of Star Trek, especially regarding the symbionts.^[37]

There are two contrasting concepts for Trill. One is that a symbiont is essentially an alien person;^[37][38] nonetheless, the joined Trill still mixes the original person with the memories and some of the personality of the symbiont.^[38] Only a tiny percentage of Trill are joined, and being accepted for the process is considered an honor.^[38] For joined Trill, a symbiont's memories, and to some extent personality, are synthesized with the existing Trill's character.^[38] Joined Trill have been studied in the philosophies of Star Trek, in particular, whether a person is essentially the sum of their memories (the philosopher Locke's "memory theory").^[39] This concept was explored in the Star Trek: Deep Space Nine television episode "Dax."^[39] (see Personal identity § Locke's conception)

The contrasting philosophy of the symbiont is called "functionalism," according to Star Trek and Philosophy: The Wrath of Kant, in which people are defined by their actions as opposed to memories.^[40] The symbionts have been dismissed as "just memories"^[41] rather than an actual person, although in other cases they are described as a "sentient symbiotic organism."^[38]

The Vidiians are encountered in the Delta Quadrant by Voyager.

In 2017, Den of Geek ranked the Vorta the 15th best aliens of the Star Trek franchise.^[13]

Vulcans are an advanced, brilliant, warp-capable humanoid species from the planet Vulcan. In the past, they were emotional and highly violent until the philosopher Surak convinced most of them to strive to suppress their emotions. War broke out between Surak's followers and those who refused to accept his teachings. Eventually, the latter left Vulcan; one of these factions became the Romulans.

While modern Vulcans still feel emotions, they consider it shameful to display or be governed by them. They seek to act by logic alone.

The Xindi /ˈzɪndi/ is the collective term for six fictional races in the science fiction television series Star Trek: Enterprise. The entire third season, broadcast from 2003 to 2004, centered on this group of previously unknown aliens. They are native to the planet Xindus in a region of space known as the Delphic Expanse. They consist of five species resembling familiar Earth animals (a rarity for alien races in Star Trek) and a sixth resembling humans. At first, they appeared as violent enemies wanting no interaction with humanity. Still, the common ground gradually emerged as the crew of the Enterprise discovered that the Xindi were being manipulated into this hostility by the Sphere Builders. Some Xindi became important recurring characters as the 24-episode story arc unfolded.

During the thirteenth live-action film in the series, Star Trek Beyond, the Xindi were mentioned along with the Romulans as aliens that humanity fought wars against in the years leading up to the formation of the Federation. Their defeat and the eventual alliance were the cause behind Edison's mutiny against the Federation, leading him to become the villain Krall.