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.
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 of galactic diversity. It's worth taking a look at a few more that even hardcore Trekkies sometimes forget about.
Tribbles
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
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
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.
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 disionate devotion to pure logic.
The Cardassians
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
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 age 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
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
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
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
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.
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
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.
