List of Star Trek aliens

Star Trek is a science fiction media franchise that began with Gene Roddenberry's launch of the original Star Trek television series in 1966. Its success led to numerous films, novels, comics, and spinoff series. A major motif of the franchise involves encounters with various alien races throughout the galaxy. These fictional alien races are listed here.

Notable Star Trek races include Vulcans, Klingons, and the Borg. Some aspects of these fictional races became well known in American pop culture, such as the Vulcan salute and the Borg phrase, "Resistance is futile."

Star Trek aliens have been featured in  Time magazine, which described how they are essential to the franchise's narrative.

X
{| class="wikitable" ! rowspan="2"|Race !Home planet ! rowspan="2"|Episodes (M = mention only) !Description Season 3 (ENT) Star Trek: Beyond M
 * rowspan="2" style="vertical-align: top;"|Xindi
 * Xindus, Delphic Expanse
 * rowspan="2" style="vertical-align: top;"|"The Expanse" (ENT)
 * rowspan="2" style="vertical-align: top;"|"The Expanse" (ENT)

The Xindi 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.

First appearance
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.

Xindi history
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.

Sphere Builders
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 species
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.
 * Xindi-Aquatics

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 boats are very slow and cannot travel much faster than Warp 2. Sunken ships also carry potent weapons and are more than a match for Insectoid and Reptilian ships. Sunken 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 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-Arboreals

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-Avians

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.
 * Xindi-Insectoids

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 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-Primates

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.
 * Xindi-Reptilians

Xindi 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 )
 * Primates: The Chairman, Degra
 * Reptilians: regimental commander Dolim

Other significant Xindi characters

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

Reception
In 2017, ScreenRant ranked the Xindi the 13th most bizarre aliens in Star Trek.

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