List of Star Trek aliens

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 a different ethnicity of the Andorian race, not a separate species.

The Aenar population is about 11,000 in size, and they inhabit the polar region of their world.

Shran's daughter, Talla, from "These Are the Voyages..." (ENT), is a mixed-race individual of Andorian and Aenar origin and greenish in color, as is the Andorian in Star Trek: The Next Generation.^{[citation needed]}

Hemmer, the first Chief Engineer on the Enterprise in Strange New Worlds, is Aenar.

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.

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.

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 by non-Benzites.

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]

Star Trek: Section 31, Quasi

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]

Star Trek: Section 31, Melle

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.^[12]

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).^[13]

In 2017, Den of Geek ranked Gorn the 23rd best alien species of the Star Trek franchise.^[14]

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.^[16]

"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 ceratopsian 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.^[20]

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.^[14]

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.^[16]

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.^[21]

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.^[22]

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.^[23]

About five hundred Ocampan generations before 2371, Nacene explorers from another galaxy inadvertently damaged the atmosphere of the planet Ocampa so badly that all nucleogenic particles were lost, thus rendering the atmosphere incapable of producing rain. The planet rapidly became a desert, a time the Ocampans later remembered as "The Warming". The Nacene left two of their kind behind to "honor the debt that could never be repaid" to the Ocampa. The male Nacene, known as the Caretaker to the Ocampa, led the endangered species through tunnels into a vast underground city constructed especially for them. The Caretaker provided them with food, entertainment, water from subterranean sources, and power from the Caretaker's array nearby in space. The Nacene then sealed the Ocampa in, using a force barrier. The Ocampa ruling Elders were subsequently charged with discovering the wishes of the Caretaker, who had become almost a deity to the Ocampan populace. By the late 21st century, the female Nacene, called Suspiria by the Ocampa, had decided to leave her mate to seek out "more interesting places." She established her own array, with a colony of Ocampa. Despite this, Ocampa history had no tales of any of them leaving or being abducted by aliens. Under Suspiria's guidance, these Ocampa colonists developed their mental talents and eventually created technology capable of increasing their natural life spans to as much as twenty years. This made them arrogant to the point that they might look at other humanoids like they looked at pets.

All Ocampa appeared to be natural telepaths, able to communicate with members of their species and those of other species, as well. Among the more unusual mental abilities exhibited by the Ocampa were eidetic memory, precognition, telekinesis of varying strength, and the ability to sense and manipulate the subatomic level of matter. Tanis, an Ocampa living on Suspiria's array, demonstrated to Kes that she could control the life force in living things, causing them to grow or die as she wished. Tanis also told Kes that the Ocampa could join Suspiria in a subspace layer called Exosia, which he described as a realm of pure thought.

In early 2374, Kes experienced a rapid and uncontrollable blossoming of her mental abilities, possibly due to experiencing intense telepathic contact with the powerfully telepathic Species 8472. Her body and everything around her, including Voyager, began to destabilize at the subatomic level. Kes left the ship and allowed this process to complete itself, apparently evolving into a being of pure energy. She could then move objects through space without need of conventional propulsion, and later exhibited the ability to travel through time. In 2376, an angry and bitter Kes, who returned to her physical form, came back to Voyager and almost destroyed it with her mental powers; only by seeing a recording of herself made before she left Voyager was the timeline changed, Kes calmed down and elected to return to her homeworld.^[24]

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.^[14] In 2020, ScreenRant ranked them the 5th smartest aliens of the Star Trek franchise.^[25]

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.

The Q are immortal, seemingly omnipotent creatures, all named Q. Q is their collective name and the name of their Continuum. One Q is particularly interested in humanity and enjoys repeatedly causing trouble for Captains Picard and Janeway and once for Sisko. The proper Q form is never seen as they claim other races cannot comprehend it.

The Q was introduced on Star Trek: The Next Generation.^[8]

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.^[26]

Species 8472 appeared in four episodes of Star Trek: Voyager.^[27] While passing through Borg space, Voyager encounters Species 8472, a race that surpasses the Borg in combat prowess.^[28]

In 2017, Den of Geek ranked Talaxians the 21st best aliens of the Star Trek franchise.^[14]

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.^[14]

Tellarites appeared rarely 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.^[29][30] They also appear in Discovery, in which Gorch, a Tellarite Starfleet admiral, is depicted.^[31][32] The animated series Lower Decks depicted a Tellarite captain in the episode "Moist Vessel."^[33] In the animated series Prodigy one of the main characters, Jankom Pog, is a 16-year-old Tellarite.^[34]

In 2017, Den of Geek ranked Tellarites the 25th best aliens of the Star Trek franchise.^[14]

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. Though they are normally extremely docile and produce a unique purring sound in the presence of humanoid species that elicits a calming effect, Tribbles produce a shrill shrieking sound in the presence of Klingons.

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.^[35] A Trill doctor, Naáshala Kunamadéstifee, appears in Star Trek: Picard,^[36] and several Trill also feature in Lower Decks.^[37][38]

Trill have been studied in analyzing the biology of Star Trek, especially regarding the symbionts.^[39]

There are two contrasting concepts for Trill. One is that a symbiont is essentially an alien person;^[39][40] nonetheless, the joined Trill still mixes the original person with the memories and some of the personality of the symbiont.^[40] Only a tiny percentage of Trill are joined, and being accepted for the process is considered an honor.^[40] For joined Trill, a symbiont's memories, and to some extent personality, are synthesized with the existing Trill's character.^[40] 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").^[41] This concept was explored in the Star Trek: Deep Space Nine television episode "Dax."^[41] (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.^[42] The symbionts have been dismissed as "just memories"^[43] rather than an actual person, although in other cases they are described as a "sentient symbiotic organism."^[40]

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.^[14]

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.

The Xindi's presence was established in the second-season finale of Star Trek: Enterprise, "The Expanse", in which the Xindi launched a probe that attacked Earth in April 2153, killing seven million people in a strip of destruction stretching from Florida to Venezuela. They appeared again in the third-season premiere, "The Xindi," to play a significant role in the primary story arc of season three.

The Xindi are a collective of six intelligent species that evolved simultaneously on the same planet (Xindus). Despite the radically different appearance of all six species, they all share identical ridges on their cheekbones and have very similar DNA. All six of these species were involved in a war lasting about 100 years and ending in the 2030s. Alliances among the Xindi species were forged and changed continuously throughout the war, so much that most Xindi forgot what started it 50–60 years into the fight. Everyone remembered how it ended, however. In desperation, the Insectoids and Reptilians detonated several charges beneath the eight most enormous seismic fissures of the geologically unstable planet Xindus, leading to its destruction and, ultimately, the extinction of the Avian race.

After the war, the Xindi scattered throughout the Expanse into several colonies. They are passionate about establishing a new homeworld and unifying all Xindi. Still, they differ significantly on how to accomplish this and who should hold the ultimate reins of power. The Xindi then spent the early part of 2153 deciding how to confront the threat of humanity and planned a biological weapon based on the human genetic profile. This was ultimately rejected by the Xindi Council (the Reptilians went ahead with the bio-weapon but were eventually foiled), so they worked on a weapon to destroy Earth. (Although they technically succeeded, the timeline in which this occurred was undone.)

In Star Trek Beyond, Krall, formerly Captain Balthazar Edison, is mentioned to have fought the Xindi and is enraged by the idea of making peace with them and other enemies such as the Romulans.

The Xindi were pawns in the Temporal Cold War, as interference in their history began shortly after the ending of their civil war, with the appearance of a trans-dimensional alien race who guided them to new homelands and resources. The Xindi came to revere these "Guardians," whom they later understood to be the same species as the "Sphere Builders." These aliens were also similarly revered by the Trianon, who believed that deities, which they called "The Makers," constructed the spheres to transform the expanse into a paradise. This led to a devastating religious civil war, as seen in the episode "Chosen Realm."

The Xindi were also informed by the Guardians, at least as early as 2152, that they would be victims of a genocidal attack from humans in the 26th century. Following their guidance, the Xindi launched a preemptive test strike on Earth as a precursor to a devastating second attack. In Daniels' timeline, Xindi crewmen serve in the Federation in the 26th century, in a battle with humans and Xindi, against the Sphere Builders. With the help of Captain Archer's evidence of future cooperation, the Xindi Council began to split over the issue of whether the Guardians were the real enemy. The split widened when Reptilian Council Member Dolim killed Primate Council Member Degra.

With the help of the Guardians, the Reptilians and Insectoids then took control of the finished Xindi weapon and set on a course for Earth, thus triggering a new civil war. A combined fleet of Arboreals, Primates, and Aquatics pursued the weapon. En route to Earth, a rift appeared in the Reptilian-Insectoid alliance when the Insectoids proposed delaying the destruction of Earth in light of Archer's revelation about the true nature of the Sphere Builders. The Reptilians determined to see the task completed and eliminated the accompanying Insectoid vessel. Arriving near Earth, an Andorian ship, commanded by Shran, suddenly destroyed the Reptilian ship, allowing humans to board the Xindi weapon and destroy it. At the same time, Enterprise was able to destroy the entire sphere network, stopping the spatial anomalies. With the Sphere Builder threat ended, the Xindi Council reconvened (the Reptilians were eventually convinced to return), and the Xindi abandoned their belief in the Guardians and their hostile intent toward humans.

Xindi-Aquatics

Xindi-Aquatics resemble Earth sirenians, swimming underwater and speaking through echolocation. Aquatics have a reputation for taking a long time to make a decision but are more readily convinced by visual evidence. The Xindi have a saying, "It's easier to count the stars than it is for an Aquatic to reach a decision." The appearance of the Aquatics in the series was inspired by the Mosasaurus.

Even though the Aquatics are peaceful, they have a strong military. Their warships resemble large Earth manta rays and are filled with water. At least one section of the ship is sealed and filled with air for land-based races. This room also has a window so the visitors can communicate with the Aquatic crew. Marine vessels can emit a field that disrupts targeting scanners. This can also be applied to protect other ships. However, their ships are very slow and cannot travel much faster than Warp 2. Aquatic ships also carry potent weapons and are more than a match for Insectoid and Reptilian ships. Aquatic warships are enormous, and one of them was depicted carrying the Enterprise NX-01 to Earth inside a chamber within the vessel after the Xindi weapon was destroyed.

Xindi-Arboreals

Xindi-Arboreals are covered with hair and resemble Earth sloths. They run kemocyte-production facilities throughout the Delphic Expanse. Gralik, a Xindi-Arboreal, gave Degra a shipment of impure kemacite to sabotage the production of the Council's weapon prototype. They have shown the least interest in destroying humanity. Arboreals are also afraid of the water. They are well-known as scientists. Jannar was a friend of Degra and an ally of Captain Archer.

Xindi-Avians

Xindi-Avians were birdlike Xindi with the ability to fly, although all that is ever seen of this species is a single skull, identical to that of a giraffe. They once darkened the skies of Xindus, the Xindi homeworld. They are considered extinct since the Reptilians and Insectoids planted explosives that destroyed the Xindi homeworld after the Hundred-Year War. The Avians, having primitive technology, could not leave the planet and were wiped out. Because of this, the Reptilians say that their lair, in which the Xindi Council now convenes, has a "stench of failure."

Xindi-Insectoids

Xindi-Insectoids resemble a cross between six-foot Earth praying mantids, flies, and ants. Insectoids have an average life span of 10–12 years. They reproduce asexually by laying eggs, which take about a week to mature. Egg sacs are suspended from ceilings, and tubules connected to them spray chemicals that cause passersby to reverse imprint on the hatchlings, protecting them as a parent would. Hatchlings are so crucial to Insectoids that hatcheries aboard starships are heavily shielded. As seen in the episode "Hatchery," the Insectoid crew will sacrifice themselves to preserve their unborn offspring.

They speak a clicking language, of which there are 67 known dialects. Insectoid iconography is radically different from that of other Xindi. Insectoid personal names get longer with age. Insectoids have a reputation for rushing into decisions. Insectoid starships are designed differently from other vessels. They don't have one area designated for bridge duties; command functions are distributed throughout the ship. Insectoid chairs and assault vehicles are designed for Insectoid anatomy and not humanoids. They have a longstanding alliance with the Reptilians, and together they destroyed the Xindi homeworld after the Hundred-Year War.

Xindi-Primates

Xindi-Primates resemble Earth humans and have a similar brain structure to the Xindi-Reptilians. They were one of the first Xindi species (including the Reptilians) to be informed of the "threat" posed by humanity. Degra, a Xindi-Primate, was assigned to develop the weapon to destroy Earth. In late 2153, the crew of the Enterprise boarded and studied a Primate's vessel and interrogated the crew. In the episode "Stratagem," Archer learned from Degra that a colony of Primates resides on Azati Prime, where the weapon was being constructed. Like humans, Xindi-Primates have differences in skin tone. The chairman of the Xindi council was a Xindi-Primate.

Xindi-Reptilians

Xindi-Reptilians resemble a cross between several Earth lizards. This species is responsible for a preemptive attack on Earth in 2153. Aided by trans-dimensional beings, the Reptilians also traveled to 2004 to collect blood samples for their bioweapon in the future but were foiled by Jonathan Archer and T'Pol. Reptilians prefer to be low to the ground instead of in highrise buildings. They use weapons with regenerative biometric power cells that overload if another species tries to use them. They use thermal chambers on board their ships to keep their energy. They are the most aggressive race of Xindi and seem more interested than the other races in destroying Earth. The military leadership of the Reptilians appears to be obsessed with eugenics. The Xindi-Insectoids is the race that the Reptilians are closest to. Along with the Insectoids, they are responsible for destroying the Xindi homeworld. The attack squadrons seen at Azati Prime consisted of two Reptilian and Insectoid ships. Commander Dolim was the Xindi-Reptilian representative on the Council.

The Xindi Council is the joint governmental body of the Xindi races, as seen in Season three of Star Trek: Enterprise. The Council was formed after the destruction of the Xindi homeworld Xindus in the 2030s. It consisted of two representatives of each Xindi species and was created to find a new homeworld for all the Xindi races. Although they found a few suitable planets, they could never agree on a final choice. The Council chamber is located on a world 15.6 light-years from Azati Prime. The land-based races sit at a large round table in the center of the room, while the Aquatics look on from a large tank adjoining the chamber by a window. The section has built-in equipment for holographic and a viewscreen for telemetry. The room was a stronghold built by the Xindi-Avians before they were wiped out.

Circa 2152, the council discovered that humans would destroy them in four hundred years. In a panic, they assigned the Primate scientist, Degra, to construct a weapon to destroy Earth. After several disagreements, the Council was dissolved. To do the Sphere Builders' bidding, the Reptilians and Insectoids broke away from the Primates, Arboreals, and Aquatics. Civil war ultimately broke out when Commander Dolim killed Degra. After Dolim was killed, the Sphere Builders were discredited, the super-weapon destroyed, and the Council reconvened. The names of council representatives as revealed in "The Council" were:

• Arboreals: Jannar
• Aquatics: Kiaphet Amman'sor
• Insectoids: unknown (most Xindi Insectoid names are unpronounceable by humans; called "Shrest" in the novelizations^[44])
• Primates: The Chairman, Degra
• Reptilians: regimental commander Dolim

• Kessick – Primate, enslaved on a Trellium-D mine
• Thalen – Primate, Degra's assistant
• Gralik – Arboreal, chief technician of kemocite facility

In 2017, ScreenRant ranked the Xindi the 13th most bizarre aliens in Star Trek.^[8]

In 2017, Den of Geek ranked Xindi the 14th best aliens of the Star Trek franchise.^[14]