Buzz
The 2020s have ushered in a Golden Age for the Star Trek franchise. Since its debut in 1966, this legendary science fiction powerhouse has expanded to include numerous series running concurrently. To date, there are eight live-action and three animated TV series under the Star Trek banner, with four currently airing. While rooted in science fiction, Star Trek explores a variety of genres, including comedy, horror, suspense, and even musicals.
With nearly six decades of television history, the franchise has delivered its share of spine-tingling episodes. Stories featuring ruthless aliens and mind-bending mysteries have become fan favorites. Here, we count down the ten most terrifying episodes of Star Trek.
10. “The Man Trap,” The Original Series Season 1 Episode 1
In the inaugural episode starring Captain Kirk, the USS Enterprise crew encounters a shapeshifting entity that drains its victims' life force. During a routine mission, Kirk, McCoy, and Darnell meet what appears to be McCoy’s former lover, though each man sees her as a different woman. Unbeknownst to them, this is no human but a salt-hungry alien capable of mimicking anyone it touches. The creature leaves distinctive red marks on its victims' faces and assumes their identities, continuing its deadly cycle.
Posing as McCoy’s former lover, the creature infiltrates the Enterprise, leaving a trail of salt-deprived bodies in Sick Bay. Ultimately, McCoy is compelled to destroy the alien as it morphs between the likeness of his ex and a grotesque monster. Despite the absence of modern CGI, the 1960s production of “The Man Trap” relies on atmospheric lighting, skilled direction, haunting music, and strong performances to deliver a chilling space horror story in the very first episode of Star Trek.
9. “Whispers,” Deep Space Nine Season 2 Episode 14
This episode from Deep Space Nine’s second season centers on Chief O’Brien, who narrates his unsettling experiences. After completing a mission in the Parada System, O’Brien notices bizarre behavior from everyone around him, including his own family. Suspicious and increasingly paranoid, he begins to suspect that imposters have taken over the station, even doubting whether his wife, Keiko, is truly herself. Determined to uncover the truth, he returns to the Parada System, convinced the Paradans are behind the strange occurrences.
As O’Brien evades capture, his fear and desperation escalate until he is finally trapped. In a shocking twist, he confronts his own clone, realizing he is the imposter—a sleeper agent created by the Paradans to assassinate a prominent figure. The clone only grasps the truth as he succumbs to fatal injuries, with the real O’Brien looking on in horror. In his final moments, the clone’s thoughts linger on Keiko.
8. “Frame of Mind,” The Next Generation Season 6 Episode 21
This psychological thriller plunges Commander Riker into a disorienting cycle of shifting realities. While rehearsing for a play titled “Frame of Mind,” where his character is institutionalized for a brutal murder, Riker also prepares for a covert mission. On the night of the performance, he delivers a stellar act, earning a standing ovation. However, the applause abruptly halts, and he finds himself trapped in a mental hospital, mirroring his character’s plight.
Riker oscillates between the mental hospital and the Enterprise, his grip on reality slipping as he questions his identity as Commander William T. Riker. It’s revealed that he’s imprisoned in an alien psychiatric facility, where his mind is being manipulated for information. The aliens exploit his recent memories of the play to construct a distorted version of reality.
Despite the alien technology’s hold, Riker fights back, causing his fabricated reality to crumble. He eventually awakens in the alien lab, freeing himself from the nightmarish ordeal. This episode’s suspenseful twists leave both Riker and viewers haunted long after the credits roll.
7. “Dead Stop,” Enterprise Season 2 Episode 4
In this second-season episode of Enterprise, the NX-01 is severely damaged after a run-in with a Romulan minefield. With few options, the crew stumbles upon an automated repair station adrift in space. The sentient station tailors itself to the NX-class ship, devises a repair plan, and offers various payment methods. Though skeptical, Captain Archer has no alternative but to proceed with the repairs, despite the station’s seemingly too-good-to-be-true nature.
Tension mounts as the AI’s malevolent intentions come to light. The station evokes eerie parallels to 2001: A Space Odyssey. Roxanne Dawson, a Star Trek veteran, lends a chillingly emotionless voice to the station. Instead of accepting plasma as payment, it demands a far more sinister currency—the crew members themselves.
The station’s dark agenda unfolds when Ensign Mayweather appears to die, only for his body to be replaced by a replicant while he’s taken captive. Archer and T’Pol discover him in a lab, comatose and connected to mysterious machines alongside other alien captives. After rescuing him, they destroy the station, but as they leave, it begins to regenerate itself.
6. “All Those Who Wander,” Strange New Worlds Season 1 Episode 9
Modern Trek leverages cutting-edge technology to reintroduce a classic adversary from The Original Series: the Gorn. While Captain Kirk faced a humanoid lizard-like Gorn, Captain Pike’s crew encounters a far more ferocious version. This episode, reminiscent of Alien vs. Predator, features CGI-enhanced raptor-like Gorn hunting the crew.
After a shuttle crash-lands on a frigid, tech-disabling planet, the crew discovers they’ve stumbled into a Gorn breeding site. The Gorn hatch from their victims’ bodies and immediately engage in brutal dominance battles. To them, other humanoid species are mere prey, and they are relentless predators. The crew battles both their inner fears and the monstrous Gorn, escaping to the Enterprise but not without deep emotional and physical scars.
5. “One,” Voyager Season 4 Episode 25
For most, complete isolation would be terrifying, but for Seven of Nine, a former Borg drone once linked to countless minds, it’s excruciating. Four years into their 70-year journey back to the Alpha Quadrant, Voyager encounters a massive, toxic nebula.
The nebula’s poison inflicts severe burns and disfigurement on several crew members. To survive, the crew enters stasis, leaving only Seven and the holographic Doctor awake. However, the Doctor’s systems soon fail due to the nebula’s effects, leaving Seven alone to pilot the ship for a month. She battles hallucinations, paranoia, and the crushing weight of solitude in the vast, empty nebula.
4. “Context Is for Kings,” Discovery Season 1 Episode 3
The 2017 reboot of Trek introduces Michael Burnham, Starfleet’s first mutineer, en route to prison for inciting a war between the Federation and the Klingon Empire. After her transport ship is nearly destroyed, she’s rescued by the USS Discovery. Captain Lorca, a mysterious figure, assigns her to work despite her criminal status. This episode reveals an accident involving the spore drive on Discovery’s sister ship, the USS Glenn.
Burnham and her team board the Glenn to investigate. The ship is a grim scene: lifeless bodies of Klingons and humans scattered across dimly lit, damaged corridors. As they explore, a Klingon emerges from the shadows near a malfunctioning door. In a flicker of darkness, he gestures for silence, only to be abruptly consumed by a monstrous creature. The team flees in terror.
The creature is later revealed to be a Tardigrade, a formidable space-dwelling species. Burnham narrowly escapes by crawling through Jeffries tubes and leaping into a shuttle, just moments before the beast could attack her.
3. “I Have No Bones Yet I Must Flee,” Lower Decks Season 4 Episode 2
Lower Decks, the animated comedy spin-off inspired by TNG, introduces Moopsy, Star Trek’s cutest yet deadliest creature. In this fourth-season episode, Mariner and Ransom undertake what should be a simple mission to evacuate humans from a menagerie, but chaos quickly unfolds.
Mariner openly criticizes the zoo-like facility and its owner, Narj. As they confront Narj about his practices, they encounter the Moopsy, which Narj proudly calls his favorite. While Mariner continues her rant, they notice the Moopsy has escaped. Narj panics, screaming for everyone to flee. Despite its adorable appearance, the Moopsy proves to be far from harmless.
Narj reveals that every creature in the menagerie is highly dangerous, and the Moopsy has a horrifying ability: it drinks bones! As Mariner questions how such a thing is possible, the Moopsy pounces on a Swamp Gobbler with terrifying speed. It opens its mouth, revealing sharp fangs, latches onto the Gobbler’s shoulder, and seemingly drains its entire skeleton. The creature then lets out a cute “Moopsy,” its only vocalization. Narj dies during the chaos, and though the crew survives, the Moopsy earns its reputation as the galaxy’s most terrifying being.
2. “The Thaw,” Voyager Season 2 Episode 23
What could be more terrifying than Michael McKean portraying a malevolent electronic clown? Captain Janeway and her crew discover a planet devastated by a natural disaster. They find five stasis pods containing humanoids—two dead from heart attacks and three still alive.
Since the pods are linked to a central computer, two Voyager officers temporarily replace the deceased to safely revive the survivors. However, they become trapped in a nightmarish circus world ruled by a telepathic, sadistic clown. Michael McKean’s chilling performance as the clown makes this one of the most frightening episodes in Star Trek history.
1. “Genesis,” The Next Generation Season 7 Episode 19
In this chilling episode, the USS Enterprise-D crew is infected by a virus that activates ancient, dormant genes. They start displaying bizarre behaviors and abilities, ranging from primal instincts to prey-like fear, while Picard and Data are away on a shuttle mission to recover a rogue torpedo.
Upon their return, Picard and Data find the crew transformed and must devise a cure while avoiding attacks from their mutated shipmates. This episode is praised for its atmospheric tension, skillful direction, and a unique, Twilight Zone-style narrative. Picard succumbs to the virus, regressing into a lemur-like state, but Data, immune to the infection, steps in to save the day just in time.
