Humans may be a hardy lot in the Star Trek universe, but they're far from the strongest. In fact, many otherworldly races are so dangerous that they are considered prime threats by Starfleet. A lot of these different races act as enemies to the Federation, while others have since mended fences, and become allies in pursuit of a greater good.

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Still, others remain as hostile as ever, with immense physical, mental, and military powers that represent a serious threat to the rest of the galaxy, if not the entire universe. The scale of danger is a determining factor when it comes to gauging just how lethal Star Trek's alien races are, and what they're truly capable of.

Updated on December 8th, 2021 by Derek Draven: Humans aren't the only species gallivanting around the Star Trek galaxy, and they're certainly not the most powerful. Many other species possess abilities that range from comparably strong, to almost God-like, and only a specific set of variables keeps them in check.

Starfleet has had encounters with many species that could wipe them out with a thought, while others have remained a persistent thorn in the side of galactic peace. Others are immensely powerful, but hold no malice or ambition, making them wild cards in terms of galactic diversity. It's worth taking a look at a few more that even hardcore Trekkies sometimes forget about.

Tribbles

Captain Kirk buried in Tribbles in Star Trek

They're cute, cuddly, and irresistible, but left to their own evolutionary devices, Tribbles represent a very real threat. These little balls of fur multiply at an exponential rate, whilst consuming all available food in a surrounding area, and they do not stop - ever.

All it takes is a small piece of food to fuel a Tribble's reproductive cycle, at which point they engulf an area with overwhelming numbers. Still, their ability to calm the human nervous system upon touch makes them a forgivable threat for many species around the galaxy.

The Xindi

A Xindi race member in Star Trek: Enterprise

The Xindi were a collection of five distinct species that were all native to the planet Xindus. The Xindi-Insectoid and Xindi-Reptilian peoples became so distrustful of each other that they both contributed to the mutual annihilation of their home world. Even after it was destroyed, they endured as a spacefaring alliance.

The transdimensional Sphere Builders guided the surviving species to habitable planets, and urged them to construct massive celestial weapons. This made them a huge threat to the safety and security of the galaxy at large, and the Xindi went down in history as one of the Federation's first real challenges.

The Vulcans

An evil Spock mind melds with Dr. McCoy in Star Trek

Vulcans were the first extraterrestrial species encountered by humans in Star Trek, and with their guidance, rose to become a major player on the galactic stage. While they are highly advanced and enlightened, they still carry some holdovers from their more primitive emotional evolution, and are not to be trifled with.

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They are known for being resilient, both mentally and physically. Many Vulcans are capable of incapacitating another sentient with a single touch, referred to as the Vulcan nerve pinch. While seemingly benign, Vulcans can be rather ruthless, cold, and calculating - a side effect of their dispassionate devotion to pure logic.

The Cardassians

A portrait of a Cardassian in Star Trek

Cardassians are a mysterious and militaristic race notorious for their ruthlessness, and their society is strictly regimented. Banana republic-style politics and kangaroo courts were a mainstay of the oppressive Communist-style regime, and the Cardassians always seemed to engage in dangerous mind games against both enemy, and friend alike.

They carried out many atrocities in their zeal to dominate the galaxy, and expand. The most serious of these was the conquest and authoritarian occupation of Bajor, in which millions of Bajorans were imprisoned, tortured, and/or executed. They became a significant threat during the Dominion War, where their militaristic talents were put to frontline use.

The Klingons

Worf and two Klingons undergo a death ritual in Star Trek: The Next Generation

Klingons are one of the most popular and enduring races in the Star Trek franchise. Their zeal for combat and glory made them a formidable military threat throughout the galaxy. Most Klingons, both male and female, are fierce fighters who undergo grueling rites of passage in order to become honor-bound warriors.

Though Klingon society is ostensibly ruled by a common sense of honor and tradition, the Empire has suffered dearly from political double-dealings and infighting. They are not fully trusted by the Federation, mostly because of their unpredictably hostile nature, which can turn them from ally to enemy at the drop of a hat.

The Romulans

Four Romulans on a remote planet in Star Trek: The Next Generation

Romulans share a common ancestor with Vulcans, but the Romulan history is much more complicated than that. Whereas Vulcans value logic and foster harmony, Romulans value ambition, and rely on cunning to advance themselves. Advancement in the military was the greatest honor a Romulan could earn.

They are best known for being masters of the long game, sometimes waiting decades to effect a master plan. Their weaponry and ship technology is on par with the Federation's best, but their cloaking technology gives them a frightening advantage in a fight. The combination of elements makes Romulans a huge threat.

The Gorn

A Gorn preparing to fight Captain Kirk in Star Trek

While reptilian in appearance, the Gorn possess a keen intellect, to the point of being able to achieve warp travel. They are also one of the strongest species in the entire galaxy, with physical feats of strength that greatly outnumber many others from different worlds. They were first introduced in classic Trek, when Kirk had to use both his fists and his brain to defeat one in combat.

The Gorn were territorial and aggressive, but not necessarily warlike. Their culture may have been xenophobic to a point, though they were later known to share in galactic events, while mingling with other species. However, very few dared to cross them.

The Tholians

A picture of a Tholian up close in Star Trek: Enterprise

The Tholians were a-non humanoid, enigmatic species first introduced to Star Trek audiences as an antagonist race. After trapping another Federation vessel, the Defiant, the Tholians attempted the same with the Enterprise. The so-called "Tholian Web" was projected and woven in space by their vessels, comprised of interconnected energy filaments.

Tholians were an instant fan favorite, despite remaining so mysterious. There were mentioned again in subsequent Star Trek series, but they didn’t reappear on screen again until Star Trek: Enterprise. Their modern appearance was akin to a crystalline spider with average height, comparable to humans. Left unchecked, Tholians are a definite threat.

The Hirogen

A Hirogen Commander talks to Captain Janeway in Star Trek: Voyager

The Hirogen were one of the most dominant species in the Delta Quadrant when the Starship Voyager encountered them in the 24th century. Much like the Yautja warriors of the Predator film franchise, the Hirogen based their entire culture on hunting worthy galactic prey.

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Physically, they were very imposing, with great height and broad composite armor. Every aspect of their technology enhanced their martial and hunting capabilities. A single Hirogen hunting vessel required a minimal crew, and could dominate regions of space spanning many light-years. They were considered an apex species in the Delta Quadrant.

The Zalkonians

Riker, Picard, Crusher and two Zalkonians in Star Trek: The Next Generation

While the Zalkonian race appears to be a seemingly ordinary humanoid species, it's their evolutionary biology that makes them so powerful. On their own, individual Zalkonians are no stronger than an average human, with comparable weapons and ship technology.

However, the Zalkonians were shown to be taking the first steps towards an evolutionary ascension in the 24th century. The Enterprise-D gave safe refuge to a Zalkonian dubbed John Doe, who was capable of healing mortal wounds, transporting himself or other beings with a thought, and resurrecting the dead.

The Prophets

A Prophet orb from Star Trek: Deep Space Nine

The Prophets resided within the stable Bajoran wormhole between the Alpha Quadrant and the Gamma Quadrant. They are sufficiently alien in the fact that emotional concepts like love, grief, and even the concept of linear time are incomprehensible to them. They are solely concerned with their own perception of the welfare of Bajor.

They can probe the minds of those to whom they grant visions, appearing as familiar figures from that person’s life, based on the type of message they want to convey. With Captain Sisko as their Emissary, they heavily shaped the course of the Dominion War, making them one extremely powerful alien species that preferred indirect action, as opposed to outright violence.

The Breen

A masked Breen on Star Trek: Deep Space Nine

The Breen are as dangerous as they are mysterious. They are only ever seen in their armored regeneration suits, and they are immune to empaths. Physically, they are devastating in combat. During the Second Klingon Empire, an entire fleet of Klingon warships invaded Breen space. Not only were they repelled, but the fleet was never heard from again.

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Even the Romulans and the Cardassians are frightened of the Breen.  They have no apparent rules of engagement and focus primarily on destroying their opponents by any means necessary. They even carried out a successful attack on Starfleet headquarters in San Francisco, at the start of the Dominion War.

The Jem’Hadar

A still of a Jem'Hadar soldier in Star Trek: Deep Space Nine.

The Jem’Hadar are a race of reptilian hybrids genetically engineered by the rulers of the Dominion in the Gamma Quadrant. Their sole purpose in life is to fight, and sacrifice themselves for the Dominion in battle. To this end, the Jem’Hadar were engineered with astounding strength and resilience, but also a rapid lifecycle.

They are most dangerous when their supply of Ketracel White runs out. The Jem’Hadar depended on this addictive narcotic for their very sanity. With it, they remain focused and obedient. Without it, they would blindly charge into battle, and even attack their fellow soldiers and superiors.

The Changelings

Odo greets another Changeling in Star Trek: Deep Space Nine

In their natural state, the Changelings are a gelatinous species capable of shifting into many different humanoid forms. Their xenophobia and isolationism became so pronounced that the Changelings established the Dominion, and sought to bring conformity and order to the entire galaxy.

Many infiltrated the Klingon and Romulan empires, as well as the Cardassians, weakening them from the outside so as to become more vulnerable to Dominion attack. Their level of cruelty was astonishing, as was their willingness to backstab any ally that wasn't a Changeling.

The Nacene

A gelatinous Nacene in Star Trek: Voyager

Star Trek viewers have only seen two members of the species called the Nacene, thus far. The one called the Caretaker was responsible for generating the displacement wave that flung the Starship Voyager thousands of light-years across the galaxy, to the Delta Quadrant.

Their technology allowed them to cross vast interstellar distances, but it also unintentionally wrought devastation on the Ocampa homeworld. The Caretaker and his mate agreed to remain as penance, protecting and nurturing the Ocampa for thousands of years. If the Nacene ever became a militaristic species, disaster would soon follow.

Nagilum

Picard speaks with Nagilum in Star Trek The Next Generation

It isn't known if Nagilum is a single entity, or a member of a race, but this extra-dimensional life form is indeed one of the most powerful in the known galaxy. After encountering the Enterprise-D in the depths of space, it set about conducting psychological and physical experiments on the crew, seemingly for the purpose of research.

Cold and unfeeling, Nagilum thought nothing of exterminating half the crew for the sake of study. Only a bold stand by Captain Picard forced it to stand down. Nagilum seems to operate under a code of ethics, though he views mortal beings the same way as scientists view lab rats, making him extremely dangerous.

The Borg

A portrait of a Borg in Star Trek: First Contact

The Borg are a cybernetic collective of humanoids focused on assimilating more species and technology into their society. In doing so, they would expand their biological and technological distinctiveness, and advance towards a goal of perfection. They are considered an implacable, relentless terror that strikes fear into the hearts of civilizations across the galaxy, and are responsible for some of Star Trek's best episodic Borg stories.

Once an individual is assimilated, their bodies and minds are reprogramed to serve the collective hive mind. Physically, they are incredibly strong, but that's nothing compared to their technology. The Borg can analyze any damage they receive, and adapt to it on the fly, rendering most conventional weapons useless against them. It's a horrifying prospect, especially given their lethal efficiency when it comes to conquering worlds.

Species 8472

A portrait of Species 8472 from Star Trek: Voyager

While they may only be known by their Borg designation, Species 8472 are a highly evolved biological terror. They are large tripedal creatures with devastating claws, keen telepathic senses, and a no-nonsense attitude. The species has developed a highly advanced form of biotechnology that lets individuals integrate with their vessels.

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Species 8472 are so lethal that they almost obliterated the entire Borg collective. With no natural defense, they were forced to team up the starship Voyager in order to develop an effective bioweapon to counter their invasion. While highly aggressive, Species 8472 is open to compromise and truce, which is their only saving grace.

The Douwd

Picard speaks to a Douwd alien in Star Trek: The Next Generation

The Douwd were an ancient celestial race of unimaginable power, though they were relatively benevolent beings uninterested in the concepts of galactic conquest or ambition. One Douwd took the form of a human male colonist named Kevin Uxbridge, who fell in love with a human woman, who became his wife.

After she was killed during an attack by a malevolent alien species, Kevin succumbed to rage, using his powers to exterminate their entire race with a single thought. His powers were unfathomable, and perhaps only the Q were capable of rivaling the Douwd when it came to omnipotent abilities.

The Q

A picture of Q overseeing a kangaroo court in Star Trek: The Next Generation is shown.

The Q, as they called themselves, are a Star Trek species of omnipotent god-like beings inhabiting a separate plane of existence called the Q Continuum. Their stated intention is not to interfere with the natural course of events in the galaxy, but this rule has been broken on many occasions, usually by rogue elements in their society.

Captain Picard and the Enterprise first encountered Q on their maiden voyage, who put them on trial for the crimes of humanity. He'd pop up several times throughout the show, creating threats both large and small. Their power is incomprehensible, yet for all their might, the Q are quite frightened of humanity, and the potential to rival them in due time.

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