Star Trek: The Essential Alien Species

Mike Delaney
TV Movies
TV Movies Star Trek

In Star Trek‘s opening narration, producers clearly established the show’s premise early on.

“… to seek out new life, and new civilizations …”

Star Trek is about exploration, and one of the most important parts of that mandate is the meeting of new and interesting alien species. Over the years, Star Trek and its spin-off shows have introduced us to dozens of unique alien races, each with their own look, history, and enduring characters.

Star Trek species including Humans, Klingons, Cardassians, Bajorans, Founders, Jem Hadar, and Vorta

Some of these species, like the Vulcans and the Klingons, have entered the greater realm of pop culture. Even people who are not fans of the series know about many of these alien species. The Vulcan nerve pinch and salute are ubiquitous within the science-fiction fan community and people endlessly parody it as well. Klingons are so well known that they have an official language, and fans have even translated some Shakespearean works into Klingon.

Here we take a look at some of the most enduring alien species of the Star Trek universe.

Andorian crew on their ship

Alongside Humans, Vulcans, and Tellarites, the militaristic Andorians are one of the founding members of the United Federation of Planets. A belligerent species, the Andorians shared a fraught history with the Vulcans. This history includes a protracted cold war that erupted into armed conflict on several occasions. The Andorian’s relations with the Humans were cemented by the respectful but antagonistic relationship between Captain Jonathan Archer and Commander Thy’lek Shran of the Imperial Guard.

The original series first introduced the Andorians, but it was not until Enterprise that they made their presence felt. Andorians hail from the frozen moon of Andoria. They have blue skin, white hair, and their most prominent trait is their twin antennae. The Andorians share their planet with a blind, telepathic subspecies known as the Aenar. With the Humans, Vulcans, and Tellarites, the Andorians were part of a multi-species effort to prevent a Romulan stealth raider from triggering wars between the alliance’s species. The alliance paved the way for the coalition that would become the United Federation of Planets.

Essential Episodes: “The Andorian Incident“, “Shadows of P’Jem“, “Kir’Shara“, “Babel One“, “United“, and “The Aenar“.


Vulcan high command have a stern chat together

Embodied by the half-Human SpockVulcans are possibly the franchise’s best known alien species. Stoic, logical, and seemingly emotionless, Vulcans embrace rational and carefully considered thought. Despite their reverence of logic, many Vulcan rituals involve spiritual elements. They have the ability to initiate telepathic mind melds, and their living spirit – or katra – can be transferred between Vulcans and even Humans.

Although many consider Vulcans emotionless, they insist that they feel emotions, they just do not let feelings control or influence their actions. Applying logic to a situation is always a Vulcan’s preferred method of approaching a situation. As a result, emotional responses from other species, especially Humans, often baffle them. Vulcans are one of the best represented alien species on Star Trek. Three of the five series aired to date including Vulcan crew members including Spock in Star Trek, Tuvok in Star Trek: Voyager, and T’Pol in Star Trek: Enterprise.

Essential Episodes: “Broken Bow“, “The Andorian Incident”, “The Forge“, “Awakening“, “Kir’Shara”, “Amok Time“, and “Sarek“.


Tellarite tries to stand up to Enterprise captain

Impatient, stubborn, pig-headed, and ugly, the Tellarites love a good argument. They consider it bad form to be polite to those they have recently met. Their preferred method of opening a conversation is through complaints and insults. In short, many consider the Tellarites to be excellent politicians. Tellarites were founding members of the United Federation of Planets, alongside the Humans, Vulcans, and Andorians.

Before the Federation’s formation, Tellarite relations with other races were less than cordial. A Romulan stealth raider threatened to incite war between the four species until a multi-species alliance was formed to track down and destroy the raider. Although introduced in the original series, Tellarites were not seen on screen again until Enterprise.

Essential Episodes: “Bounty“, “Babel One”, “United”, and “Journey to Babel”.


Klingons look at a monitor baffled

Klingons live for battle. The warrior spirit flows through them, and satisfaction of personal honor drives a Klingon’s life. They are formidable warriors, and there is nothing more honorable than victory. Klingons prefer close, personal combat using their edged weapons – the two-bladed bat’leth, the single bladed mek’leth, or the d’k tahg dagger – to inflict damage on their enemies. Klingons build their starships for combat and arm them with torpedo launchers, disruptor banks and cloaking devices for sudden, swift attacks.

However, Klingons are not above compromising honor to preserve the Empire. The Klingon High Council willingly slandered the name of Worf’s father. High Council did this to avoid placing the public blame on the true culprit, the father of the politically powerful Duras. The Council believed that Worf’s status as a Starfleet officer would stop him from contesting the charges. So Worf accepted the discommendation from the Klingon Empire to avoid a civil war. But the corruption ran deep, with Chancellors such as Gowron putting personal honor above the interests of the Empire. Some Klingons lamented the loss of other aspects of Klingon culture such as the legal profession for the way of the warrior.

Essential Episodes: “Broken Bow”, “Judgment“, “Affliction“, “Errand of Mercy“, “The Trouble with Tribbles“, “Day of the Dove“, “Sins of the Father“, “Redemption“, “Blood Oath“, “Way of the Warrior“, and “Taking into the Wind“.



Romulans are an offshoot of the Vulcan species, and share many of their physical traits. They occupy the twin worlds of Romulus and Remus, subjugating the native Remans. Their society is structured and ordered with a strong military, effective intelligence arm, and ruled by a representative Senate. Subterfuge and infiltration are key weapons in the Romulan arsenal. They possess powerful cloaking devices that allow their ships to move undetected through the galaxy and power their starships with artificial singularities.

Romulans are secretive and often work behind the scenes to destabilize their enemies. Romulan deceit and treachery is legendary. Despite fighting a war with Humans, the Federation did not know what a Romulan looked liked until the mid-22nd century. For much of the 23rd century, the Romulans cut themselves off from the galaxy. They broke their self-imposed isolation upon the destruction of their outposts along the Neutral Zone, possibly by the Borg.

Essential Episodes: “Minefield“, “Babel One”, “United”, “The Aenar”, “Balance of Terror“, “The Enterprise Incident“, “Unification”, “In the Pale Moonlight“, and “Inter Arma Enim Silent Leges“.



Initially introduced in The Next Generation, writers intended the Ferengi to be a new major recurring threat for the crew. Unfortunately, they did not resonate with fans and the production shelved plans to continue their development. Subsequently, they retooled them into a more comical role. Acquiring wealth drives the Ferengi. The

Acquiring wealth drives the Ferengi. The Rules of Acquisition rule their lives and business dealings, and there are guidelines for nearly every conceivable situation. Ferengi have no qualms about swindling customers to achieve the best deals.

Ferengi society is heavily biased against females. For a long time, society forbade Ferengi females to wear clothes or earn their own profit. Reformations to Ferengi society began to redress these issues after many females proved they had a head for business.

Ferengi dabble in a wide range of business ventures and do not worry about the legality of said business. They are often arms dealers and smugglers, and even Ferengi like Quark who runs a bar on the Federation-controlled space station Deep Space Nine was known to engage in illegal activity, much to the chagrin of local authorities.

Essential Episodes: “The Last Outpost“, “The Nagus“, “Rules of Acquisition“, “Family Business“, “Body Parts“, “Ferengi Love Songs“, and “The Magnificent Ferengi“.



Deeply spiritual and religious, the Bajorans worship the Prophets. Despite the revelation of their true nature as non-corporeal, non-linear alien beings who learned to love baseball, Bajorans still revere the Prophets. The Cardassians annexed the Bajoran homeworld of Bajor, and they occupied the world for 50 years before withdrawing. The Bajorans fought a bloody insurgency to free their homeworld. Many Bajorans felt betrayed by the Provisional Government when they invited the Federation to take control of an orbiting space station abandoned by the Cardassians and renamed Deep Space Nine.

Bajoran society began the painful rebuilding process, and by recommendation of Captain Benjamin Sisko, remained neutral during most of the Dominion War. Post-occupation Bajor was fraught with internal conflict as opposing factions sought to control the newly-freed planet. The discovery of the wormhole to the Gamma Quadrant established the Bajorans as a power in the Alpha Quadrant. However, they relied on the presence of the Federation to legitimize their claim.

Essential Episodes: “Ensign Ro“, “The Emissary“, “Duet“, “The Homecoming“, “The Circle“, “The Siege“, “Shakaar“, “Accession“, and “Tears of the Prophets“.



The militaristic Cardassian Union is effectively a police state ruled by the military Central Command and the intelligence arm known as the Obsidian Order. A civilian government known as the Detapa Council is the “official” governing body of the Union but, in reality, has little power. All criminal trials within the Cardassian Union are for show only – officials decide the trial verdict in advance.

The Cardassians annexed and ruled Bajor for 50 years. During the occupation, they committed countless atrocities, and Bajoran society struggled to rebuild in the wake of their departure. The post-annexation years saw Cardassian fortunes flounder; rumors of a Founder takeover of the Cardassian government led the Klingons to declare war and ravage Cardassian space. Left with little choice, they allied with the Dominion and fought the combined Federation, Klingon, and Romulan forces. In the last stages of the war, the Cardassians rebelled against their Dominion allies as the Dominion would often use Cardassian forces as expendable assets.

Essential Episodes: “The Wounded“, “Chain of Command“, “Duet”, “Defiant“, “The Way of the Warrior”, “Return to Grace“, and “The Dogs of War“.



The Enterprise-D crew first encountered the Borg in the episode “Q Who“. They quickly established themselves as a true threat to the Federation. Borg are a collection of species assimilated into a shared hive consciousness. They are relentless, terrifying and virtually unstoppable (until serious villain decay took hold in

Borg are a collection of species assimilated into a shared hive consciousness. They are relentless, terrifying and virtually unstoppable (until serious villain decay took hold in Voyager). They exist solely to assimilate technology and biological lifeforms into their collective in an effort to raise all species to “perfection”. A queen rules the Borg, and their imposing vessels are simple geometric shapes. Even one ship could be considered an invasion.

Responsible for multiple incursions in Federation space, the Borg fought Starfleet at the Battle of Wolf 359 and the Battle of Sector 001. They even attempted to stop First Contact between the Humans and the Vulcans through the use of time travel which resulted in an awesome movie. The Borg invasion of the Federation is probably the result of the pre-destination paradox. The Borg became aware of Earth because Borg drones in the past who survived the attempt to stop First Contact sent a communication to the Delta Quadrant. This alerted the collective to the presence of the planet. So the Borg investigate, leading to the events that cause the drones to travel to the past in the first place.

Essential Episodes: “Regeneration“, “Q Who”, “The Best of Both Worlds“, “First Contact“, “Scorpion“, “Dark Frontier“, “Unimatrix Zero“, and “Endgame“.



Introduced in the final episode of Enterprise‘s season 2, the Xindi became the primary antagonists for season 3. Time-travelling Guardians warn the Xindi that Humans would destroy them in the future. So, the Xindi build a weapon that destroys a section of Earth from Florida to Venezuela, killing seven million. Now forewarned of the Xindi intent to destroy Earth, the Enterprise head to the Delphic Expanse to stop them. Humanity would eventually stop the Guardians’ plans in the future, so they lied to the Xindi to eradicate all Humans. Eventually, everyone becomes friends, and the Xindi join the Federation.

Unlike most of the major alien races, the Xindi are not a single species, but six distinct species. These are the Avians, the Arboreals, the Primates, the Aquatics, the Insectoids, and the Reptilians. Despite their vastly differing outward appearance, the Xindi species share over 99.5% of their DNA. By the time the Enterprise encounters the Xindi, the Avians are extinct, and a Council that includes representatives from all five Xindi species governs the remaining five.

Essential Episodes: “The Expanse“, “The Shipment“, “Proving Ground“, “Azati Prime“, “The Council“, “Countdown“, and “Zero Hour“.

Mike Delaney
Star Wars fan and general pop culture addict. Only two beverages worth drinking are tea and whisky.
Become a
Pop culture fans! Write what you love and have your work seen by millions.