Star Trek Stories That Are Actually Horrifying

Among the longest-running franchises in TV and movie history, "Star Trek" may be an outer space adventure, but it often defies genre categorization. While every episode and film is science fiction by nature, individual stories run the gamut. Across its many series and through nearly 60 years, "Trek" has embraced everything from mystery and action to romance and even comedy. One genre that has long been a staple of its storytelling is horror: tales that shock and frighten, with scares and suspense as effective as any monster movie or salacious slasher.

In fact, many of the best stories in "Star Trek" are of the hair-raising variety, from those set aboard spooky derelict starships to those where a mysterious creature stalks the crew. Whether in a movie or a show, moments that shock with disturbing imagery or scare with spine-chilling thrills are often the most memorable. 

Which of these terrifying tales are the best, the most blood-curdling, and the most downright horrifying? Your mileage may vary depending on what sends you scurrying, but here are some of the best "Star Trek" stories that are actually terrifying.

Despite being the darkest of the '90s "Star Trek" series, tackling more serious subject matter, and enjoying a more grim tone, "Star Trek: Deep Space Nine" rarely ventured into straight horror. On the few occasions it did, it went hard. "Empok Nor" is the perfect example. It features some of the franchise's best edge-of-your-seat suspense, loads of jump scares, and as much blood-curdling imagery as they could get away with by '90s broadcast standards. 

The episode starts with the former Cardassian space station Deep Space Nine in dire need of repair. Unable to simply ask the Cardassians for replacement parts since they're in the middle of a war with the Dominion, the crew's only choice is to salvage components from its derelict sister station, Empok Nor. Chief O'Brien assembles a team to travel to the abandoned station, taking with him the gung-ho Ferengi cadet Nog and the former Cardassian spy Garak.

When they arrive, the team discovers they are not alone, and they're picked off one by one by what they discover are Cardassian soldiers who've been re-engineered into soulless killing machines. Garak takes it upon himself to hunt them down but risks becoming one of them. More than just a violent slasher, the story also explores O'Brien's history during the Cardassian war and the prejudice that still remains between the two sides. Above all, it's a story of O'Brien and the young cadet who must stay alive against a group of ruthless, bloodthirsty killers — and their own friend Garak, who may no longer be on their side. 

The second film starring the cast of "Star Trek: The Next Generation," "Star Trek: First Contact" is sometimes mistakenly considered an action movie because it features Captain Picard with a phaser rifle stalking the ship like John McClane. At its heart, "First Contact" is a horror story. It sees the return of the mindless cyborg race in a big-budget feature film that turns them from a series of insect-like drone robots into a horrific zombie army, visually redesigned to look scarier and more monstrous than ever before.

It begins with the Borg launching an assault on Earth as Picard and the Enterprise race to stop them. When the enemy ship uses a temporal vortex to travel back in time and conquer the planet in the early 21st century, the Enterprise follows. While Riker, Geordi, and Counselor Troi deal with restoring history by enabling scientist Zefram Cochrane's first test of a warp drive, Picard, Data, and Cochrane's assistant must deal with the Borg, who have taken over the ship and whose mere touch can lead to assimilation and death. 

That's all pretty scary, but it's the discovery of the Borg queen that makes the film a true horror tale. A sinister and demonic villain unlike anything "Trek" had seen before, she not only plays on Picard's worst fears, but also twists the android Commander Data by tempting him with mortal flesh. A mix of "Hellraiser" and "Night of the Living Dead," it might have been a horror classic had it not been a "Star Trek" spin-off.

Perhaps one of the most underrated episodes of "Star Trek: The Next Generation," "Remember Me" isn't just a mind-bending roller coaster and rare Dr. Crusher episode; it's also a nightmare come to life. Like a literal dream reality that you wish you could wake up from, the episode's surprising twists and turns will leave your head spinning. 

While her son Wesley performs experiments in engineering, Dr. Crusher and the Enterprise arrive at a starbase to take on new personnel, including her Starfleet professor friend, Dr. Dalen Quaice. When Quaice mysteriously disappears, and nobody but Crusher appears to remember he ever existed — including Starfleet — the good doctor fears she is losing her mind. It soon becomes clear that something strange is afoot, as more people aboard the ship begin to vanish from existence, from her own medical staff to senior officers like Lt. Worf and Commander Riker. As the crew dwindles to just the doctor and Captain Picard, nobody seems to think anything is wrong.

All the while, however, Dr. Crusher finds herself running from a strange vortex that appears and disappears throughout the ship, apparently threatening to erase her from existence. Now it's a frightening race against time to unravel the mystery before all of reality collapses in on itself. A terrifying "Trek" story that explores our greatest fears, "Remember Me" is an unheralded "Trek" gem.

Despite its reputation as an action-oriented series — and one that never went as dark as its sister show "Deep Space Nine" — the '90s spinoff "Star Trek: Voyager" probably did more horror-themed episodes than any "Trek" series. From psychological thrillers to stories of demonic possession, "Voyager" constantly crossed genres, and the Season 4 episode "Revulsion" was the show's version of a slasher movie, complete with disturbed psycho killer. 

The story opens with Voyager receiving a distress call from a nearby vessel and heading to investigate. What they find is not a ship in trouble, but a holographic crewman named Dejaren who is the apparent lone survivor of a deadly viral outbreak. After his humanoid shipmates all died, his limited functionality left him with no idea what to do next. Excited to meet another of his kind, Voyager's resident holographic Doctor tags along with Chief Engineer B'Elanna Torres to help make repairs to the ship. Dejaren is skittish and paranoid, and his disgust for organic beings is obvious, forcing Torres to wonder if it was really a virus that killed the crew.

When the mentally unstable Dejaren snaps and seriously injures Torres in a homicidal rage, it's up to the Doctor to keep her alive long enough to disable the hologram's program and stop him from finishing the job as he hunts them through the ship. A violent, terrifying thriller, the only thing holding this one back from true greatness is a weak subplot involving Harry Kim's crush on Seven of Nine.

Launched in 2022, "Star Trek: Strange New Worlds" was described by its creators as a return to the optimistic and upbeat storytelling of classic "Trek." That doesn't mean it couldn't go dark. Through its first season, it became clear it would tackle every stereotypical "Star Trek" story, horror included. Its entry in that genre was "All Those Who Wander," a frightening tale that's a clear homage to sci-fi horror classics like "Alien" and "Predator."

As the Enterprise heads to Deep Space Station K-7, Starfleet orders Captain Christopher Pike to divert to a Class L ice planet called Valeo Beta V, where the U.S.S. Peregrine has apparently crashed. While the Enterprise heads for the station, Pike, Spock, and a small team stay to investigate the downed Starfleet cruiser and the deaths of its entire crew. 

Pike finds only an unidentified alien and a small human girl, who claims the human crew of the Peregrine were all lost when Gorn hatchlings emerged from the body of a fellow refugee, quickly hunting and killing the crew. When the unidentified alien himself births a litter of Gorn young, Pike and crew must fight for their lives as the inhuman monsters stalk them through the bowels of the downed ship. Full of more than just jump scares, the episode culminates with the surprise death of a major character and proves to be one of the premiere season's best entries.

In another episode that begins with the discovery of a starship left adrift, Picard and the Enterprise come across the U.S.S. Brattain, which has been missing for some time. Aboard the ship, they find only one survivor, a Betazoid who is so in shock from what happened on his ship that he is left mute. The rest of the crew is dead, with Dr. Crusher finding evidence that they all killed each other, either with phasers or their bare hands. The captain's final log entry shows that the crew had gone insane, becoming paranoid and violent, but the doctor can find no cause as to why.

While Counselor Deanna Troi attempts to communicate telepathically with the survivor, getting only half-intelligible nonsensical phrases, the Enterprise crew begins to suffer effects themselves. Some begin to hallucinate, while others become so fearful and anxious that they turn on one another. As their condition deteriorates, Troi begins having uncontrollable nightmares of a glowing pair of orbs and a disembodied voice crying out a singular repeating phrase: "Eyes in the Dark. One Moon Circles."

With Commander Data and Troi somehow unaffected, they must work together to find out the meaning of her visions before the crew devolves into murderous insanity. A disturbing and haunting episode punctuated by an eerie musical score — and an unforgettable sequence where an entire morgue of dead bodies comes to life — "Night Terrors" is not an episode to be watched in the middle of the night.

When "Star Trek" goes body horror, it does it with aplomb. The first season "Voyager" episode "Faces" is a prime example. The series cleverly prepared for this entry, introducing Lieutenant Durst one episode earlier so that the horrific events of "Faces" would seem all the more intense. Centered on half-Klingon engineer B'Elanna Torres, the episode sees the return of the series' recurring villains, the Vidiians, who suffer from a brutal disease called the Phage. Ravaged by the affliction, Vidiians are forced to augment themselves with healthy tissue from the bodies of living victims. They have become the scourge of the Delta Quadrant, kidnapping innocent victims and mutilating them to steal their body parts. 

In "Faces," Torres and Durst are taken prisoner by a Vidiian scientist and surgeon named Sulan who believes that pure Klingon DNA may be resistant to the Phage. Using his genetic expertise, he finds a way to separate Torres into two individuals: one fully human, the other fully Klingon.

While much of the episode revolves around Torres using the experience to come to terms with her Klingon ancestry, the meat of the episode focuses on Sulan's growing attraction to the Klingon woman. After killing Durst to steal his organs, Sulan takes the Lieutenant's old face and grafts it onto his own in one of the creepiest moments in the series. A shocking mad scientist episode, "Faces" plays like a "Star Trek" homage to the work of David Cronenberg.

When it comes to "Star Trek: Enterprise," there are a number of creepy episodes that might qualify for this list, including "Vanishing Point" (where Hoshi Sato believes she's disappearing from reality) and "Dead Stop" (where a suspicious automated space station appears to be killing the crew). But the most terrifying is certainly "Impulse," a little monster movie from the series' third season. 

Set at the beginning of the Xindi War story arc, the episode shows the Enterprise approaching a dangerous region of space called the Delphic Expanse, from which no ship has ever returned. Sub-commander T'Pol tells the tale of the Vulcan starship Seleya, lost in its confines of the Expanse a year earlier.

The Enterprise discovers the Seleya adrift in an asteroid belt rich in a rare ore called trellium, which could protect the ship from the effects of the anomalies in the Expanse. When they go aboard, they discover what happened to the ship's crew as they are attacked by a vicious Vulcan who has been driven mad by the effects of the unique ore. The fight to get back to the Enterprise is complicated by T'Pol, who also begins to suffer from the effects of the trellium, turning her against them. It's a classic "cabin in the woods" scenario, only set on a starship in outer space.

Though it never goes down the truly horrifying slasher route it could have, "The Haunting of Deck 12" is nevertheless a scary story told as a kind of campfire tale. It begins with happy-go-lucky hobbit-like alien Neelix entertaining a group of children by lantern light in a closed-off cargo bay while the ship undergoes some kind of crisis. Flashing back, it seems the Voyager traveled past a unique nebula, after which a series of minor malfunctions began plaguing the ship.

Decidedly not played for laughs, the misbehaving systems are unsettling and hint at something more sinister at play. Soon the ship's malfunctions become dangerous, nearly killing members of the crew. These are no mere systems on the fritz: when they passed by the nebula, the ship picked up an unintended stowaway in the form of an energy-based life form that's trying to make the ship habitable for itself. As Voyager is quickly filled with the same poisonous gases as the nebula, the crew is forced into more remote areas of the ship in an attempt to stay alive.

As time runs out and control of the ship is lost, Janeway must find a way to communicate with the entity before it kills everyone on board. Though the episode could probably have used a few more red-shirt deaths to hammer home the danger, "The Haunting of Deck 12" remains a suitably spooky ghost story and gives Janeway several fierce moments as she wades into a battle of wills with a killer energy cloud.

Set more than 100 years before the original series, "Star Trek: Enterprise" surprisingly featured the "TNG" foes the Borg in the Season 2 episode "Regeneration." An unexpected follow-up to the 1996 film "Star Trek: First Contact," the episode opens with a team of scientific researchers in Earth's Arctic region discovering the remains of the Borg vessel that had crashed there in 2063 after having traveled back in time. The researchers have no idea what the debris is and are unaware that the two bodies they've recovered are dormant Borg drones.

The franchise's version of John Carpenter's "The Thing," this episode features elements of horror and increasing tension as a monster awakens beneath the ice. The first half of the story focuses almost entirely on the scientists and their desperate attempt to fight off the zombie-like Borg monsters as they slowly regenerate their frozen forms. Once assimilated, the researchers form a new mini-collective with the two Borg and build a new spaceship to take them to the Borg that exist in this era. As they set out on a direct course for the Delta Quadrant, it's up to the crew of the Enterprise to stop them, even if Captain Archer doesn't know the true danger that this race of cybernetic monsters poses. 

The dramatic irony and nail-biting suspense, combined with classic zombie horror, make "Regeneration" one of the best episodes of "Enterprise," while riling up canon-obsessed fans at the same time.

A classic "boogeyman" episode, the "Next Generation" Season 6 entry "Schisms" opens with a tongue-in-cheek scene featuring Data reciting the poem "Ode to Spot" to a gathered audience. Among those listening is Riker, who is unable to stay awake. This is more than just boredom, as the phenomenon begins to spread and more crewmen suffer the effects of sleep deprivation despite getting extra rest. 

Before long, Riker, Worf, Geordi, and others begin showing signs of post-traumatic stress. Even Commander Data learns that his internal chronometer is showing a gap in his memory. As disturbing images begin to haunt several members of the crew, they realize something is very wrong. Counselor Troi uses the holodeck to try to reconstruct their fragmented memories. They're able to deduce that someone or something is abducting them while they sleep and subjecting them to a bizarre form of experimentation or torture. Unable to stop it, Riker volunteers to allow himself to be taken again in the hopes of leading them to the source of their monstrous tormenters and saving an abducted crew member.

Featuring some of the most unsettling scenes in "TNG," the episode is sure to send shivers down the spine of anyone who's feared an alien abduction, or whether their own memories could be hiding a horrifying secret.

The "Deep Space Nine" Season 5 episode "The Darkness and the Light" isn't just grim, but also terrifying, following a deranged madman's lust for revenge. Amid an ongoing story involving a pregnant Major Kira, word comes that a former soldier from her time as a resistance fighter against the Cardassian occupation has been killed. Just when she's mourning her comrade, the major receives a mysterious transmission in a garbled voice declaring, "That's one." Whoever sent it is on a mission to assassinate every member of the Shakaar resistance.

The stakes are raised as victims two and three are reported and more messages arrive that make it clear her time is running out. Unwilling to wait for her death, Kira sets out to find her killer first. It doesn't take long to find him, as she is immediately abducted upon arriving on the doorstep of Silaran Prin, a Cardassian merchant who had been disfigured in a bombing perpetrated by her resistance cell.

The rest of the episode, and the crux of the horror, is a chilling game of wits — a mental cat-and-mouse game — between Kira and her torturer. It's not just Kira who is at risk, but also her unborn child. The atrocities of war, the visage of the disfigured Prin, and the diabolical deeds he threatens are enough to terrify anyone.

The "Next Generation" episode "Genesis" rightfully enjoys a reputation as a body horror episode and one of the scariest episodes of the series. What makes the episode so effective is just how slowly the danger builds. It begins innocently enough, showing a series of everyday occurrences of life aboard the Enterprise. But while Picard and Data take a shuttle to retrieve a stray torpedo, an unusual virus begins sweeping the ship.

At first, the effects are odd but benign: Barclay becomes fidgety and Riker somewhat forgetful. Their behavioral aberrations quickly and precipitously increase while the ship's systems begin to fail. Things become dangerous when Worf attacks Dr. Crusher, blinding her with deadly acid. By the time Picard and Data return, the Enterprise is adrift. When they come on board, they find the ship's helmsman viciously mauled, as if by a large beast. Data deduces that the crew has been infected with a virus that has "de-evolved" them into more primitive forms of life, with Troi growing gills and becoming a reptilian creature and Riker mutating into a Neanderthal.

The biggest danger is a massive monster that they realize is Lt. Worf, who's stalking them through the ship. Picard may have to sacrifice himself if he's going to buy Data enough time to find a cure. With mayhem, murder, and a fiendish monster following Picard, "Genesis" is as close to a classic monster movie as "Trek" has ever come.

When "Star Trek" was relaunched on the small screen in 2017 with "Star Trek: Discovery," it took the franchise in a bold new direction, with a serialized story and more adult sensibility. But there were still plenty of classic "Star Trek" elements, as its third episode used a tried-and-true formula and dove back into the well of horror with another monster-of-the-week story. 

In some ways, "Context Is for Kings" is the first episode of the series, as the two-part premiere was a self-contained set-up of the premise. Here, Commander Burnham and her new enigmatic captain Gabriel Lorca investigate the wreckage of the USS Glenn, Discovery's sister ship, which is also equipped with an experimental spore drive. Something has gone wrong on the Glenn; when they arrive, they find that the crew has been horribly deformed and turned inside out, possibly as a result of testing their experimental propulsion system. That's not all: also on board is a group of dead Klingons, all apparently maimed by a mysterious beast that's still around. With some of the goriest visuals seen in a "Trek" series to date, the episode is among the franchise's most viscerally horrifying in more ways than one. 

Another episode of "Voyager" centered on B'Elanna Torres, "Juggernaut" once again sees the engineer face off with a vicious antagonist who forces her to confront her more aggressive Klingon nature. Unlike the previous tale, the baddie in "Juggernaut" is not a mad scientist, but a mysterious monster haunting a damaged alien vessel. 

Coming to the aid of the Malon — the scourge of the Delta Quadrant whose waste haulage is a hazard to anything within its reach — the crew learns that the engine of their freighter is on the verge of critical collapse. If it can't be repaired, the radiation from their waste cargo will destroy everything within several light-years. Determined to restore the ship's containment field, Torres and a repair team go aboard and begin the perilous journey to the heart of the ship, where one of the Malon officers believes a legendary creature resides. As they grow nearer, they learn that this beast is no myth. They must contend with its violent rage if they are to repair the ship and save the sector.

In addition to its thrills and spills, "Juggernaut" also boasts a powerful environmental allegory. A monster mash with a moral message, the episode is packed with plenty of social commentary in the best tradition of classic "Trek."

Not all things that are scary must be visually horrifying, nor do they even have to cause a sudden shock. Some of the most frightening stories, in fact, explore our darkest, deepest fears, and those feelings can run the gamut of emotion. Arguably there are few feelings more terrifying than loneliness, and that's the subject of the "Star Trek: Voyager" episode "One." At the center of the story is newly-recruited Voyager crew member Seven of Nine (Jeri Ryan), a former Borg drone still struggling to rediscover her humanity.

As the episode begins, the ship must traverse a dangerous region of space brimming with fatal radiation, and to survive, Captain Janeway orders all hands into the ship's stasis chambers. The holographic doctor is to monitor the crew's life signs during the trip, while Seven of Nine's Borg implants also allow her to remain awake to assist in keeping everyone alive. But when the radiation causes the ship's vital systems to begin breaking down, the Doctor's holo-program disappears. Now, Seven must save the crew while coming face to face with her re-emerging human emotions.

"One" is a spine-tingling episode with Seven of Nine slowly losing her mind as we begin to wonder what's real and what's part of her paranoid delusions — including a nefarious alien visitor. If that wasn't enough, the episode is also a sinister story of solitude, loneliness, and the desperate need for human contact. 

"Star Trek: Enterprise" didn't do as many horror-themed episodes as "Voyager" or "Deep Space Nine," but the series might have more inherent creepiness than any other, thanks to the fact that the NX-01 Enterprise is all alone with no friendly alien races and no starbases. When it comes to chills, few episodes in the show go as deep as the third season installment "Dead Stop." Following the previous episode, "Minefield," the story opens with Captain Archer and the NX-01 Enterprise badly damaged, with no warp drive and in desperate need of repair.

Good fortune strikes, though, when a Tellarite ship contacts Archer with coordinates for an alien repair station that can help them — for a price. What they find, however, is a strange automated station with wondrous technology far ahead of their own (but quaint by "Next Generation" standards). Reed and Tucker want to find out how this new technology works, but their efforts are repeatedly thwarted by the station's eerie artificial intelligence. 

Things go from strange to scary when Ensign Mayweather is killed under suspicious circumstances and Archer and crew begin to fear that the cost to fix their ship may be paid in blood. When they try to sever their connection to the station, it triggers a response that could destroy the entire crew. A taut thriller, "Dead Stop" balances hair-raising tension with electrifying suspense and even a couple of genuinely jaw-dropping twists.

Thanks to its stellar first year — which landed at the top of our ranked list of "Trek" first seasons — "Star Trek: Strange New Worlds" quickly got a second. One key episode from the show's sophomore year proved that they weren't done with the horror genre. That episode is "Hegemony," the epic Season 2 finale, and a follow-up to Season 1 entry, "All Those Who Wander." That episode saw the crew facing off with a pack of bloodthirsty Gorn, and this season-ender brings the reptilian aliens back with a vengeance.

In "Hegemony" we find Captain Pike's on-again/off-again lover Captain Batel and the USS Cayuga visiting a remote Federation colony that resembles a quaint 20th-century American town. Things appear normal until a Gorn starship emerges from the sky, and suddenly it's up to Pike and the Enterprise to save the colony. When they arrive, though, they find only the bloody remains of the colonists and Starfleet personnel. 

Ultimately, "Hegemony" is another horror movie, with the monstrous alien Gorn in the role of the ruthless slasher villain. Written by series showrunner Henry Alonso Myers, the episode is dark, grim, and soaked with human blood as Gorn warriors tear through the colonists and leave Pike with little choice but to abandon the planet — while Batel remains a captive of the enemy. "Hegemony" ups the scare factor from "All Those Who Wander," while its showstopping cliffhanger ending will leave your hair fully raised.

It might not be among the best-rated entries in the franchise, but "The Thaw" may just be one of the most underrated episodes of "Star Trek: Voyager." This second season tale centers on a homicidal clown, making comparisons with the classic horror novel "It" and its screen adaptations easy. But it definitely puts a "Star Trek" twist on the horrific proceedings. 

Captain Janeway's nightmare begins when Voyager detects a distress signal of sorts from a nearby planet. When they arrive they find a group of individuals in a form of suspended animation and their minds connected to a computer simulation of their own, lifelike reality. To free them, Ensign Kim and B'lanna Torres must go into the simulation themselves, and when they do they discover an evil computer program that's taken the form of a sadistic clown.

Inside the simulation, the Clown feeds off the fear of his victims, leading to escalating levels of torture at the hands of his high-spirited henchmen that appear as members of his circus. Though the episode is relatively bloodless — something that defangs it somewhat — it's nevertheless one of the most chilling tales "Voyager" ever produced. If you've ever felt genuine fear — whether it was being afraid of clowns, afraid of the dark, or just afraid of losing a loved one — then "The Thaw" will probably keep you up nights.

"Star Trek" has tackled many disturbing themes and stories, from racism to sexual assault to even apartheid and genocide. In Season 2 of the 2020 series "Star Trek: Picard," they took on an issue that had rarely been explored: childhood trauma. That year, the show delved into the dark past of Patrick Stewart's titular Jean-Luc Picard, revealing that the difficult relationship he had with his abusive father may have been more than what it appeared on the surface. In the episode "Monsters," the former Enteprise captain must confront the truth of the horrific trauma he faced as a young boy growing up in France.

In "Monsters" we get direct flashbacks to Picard's childhood, where we learn that his mother Yvette had real struggles with her mental health, ending only when she took her own life. The young Picard, in his naivete, had played a role in her death too, something that Jean-Luc must now come to terms with, while accepting that he wasn't to blame. It's a dark exploration of Picard's backstory that can be difficult to watch, especially if you've ever been even remotely connected to an abusive or mentally disturbed family member. Though its scare factor is unconventional, the episode presents trauma as the terrifying reality that it is, while finally resolving longstanding questions about Jean-Luc Picard's timeline.

If you or someone you know needs help with mental health, please contact the Crisis Text Line by texting HOME to 741741, call the National Alliance on Mental Illness helpline at 1-800-950-NAMI (6264), or visit the National Institute of Mental Health website.

"Star Trek: Deep Space Nine" might have produced the largest amount of scary stories because it didn't just embrace the horrors of space, but the horrors of war. It also explored religion through the narrative of two ancient and godlike alien races at war over the planet Bajor. Their battles were typically fought on a more spiritual plane, but in "The Assignment" the conflict takes physical form.

It all begins when Chief O'Brien's wife Keiko returns from a trip and claims to her husband that she is not his wife at all. Instead, she claims that she is one of the ancient Bajoran Pah Wraiths, who oppose the more benevolent Prophets. She has possessed Keiko's body and wants O'Brien to sabotage the station or she'll kill her host. At first, the sabotage seems harmless, so O'Brien attempts to comply. But as the pressure mounts and threats are made against him when he tries to alert the rest of the crew, the Pah Wraith's diabolical plan is revealed to be anything but benign.

O'Brien is left with a gut-wrenching choice, since to save the station he may have to let his wife die. The episode's darkest scene, however, comes when the Pah Wraith — in Keiko's body — slyly threatens the life of their young daughter Molly in full view of the station crew. One of the most nail-biting suspense stories "DS9" ever produced, this one will leave you on the edge of your seat until the show's final moments.

Younger audiences may need to ignore some awkward '60s sexism to enjoy the classic episode "Wolf in the Fold." Sadly, inadvertent misogyny wasn't uncommon for the original "Star Trek" series — which was very much a product of its time despite its overtly progressive leanings. So it's somewhat cringeworthy when the Enterprise visits Argelius II, a hedonistic pleasure planet where chief engineer Scotty can overcome his apparent resentment towards women. But after Scotty spends a sexy evening with a lovely lass, he later turns up standing over her dead body and holding a blood-stained knife — and he's quickly accused of a murder that he doesn't remember committing.

Soon a Starfleet medical officer helping with the investigation also turns up dead, apparently stabbed by Scotty with the same bloody knife. Suddenly there is little doubt that the Enterprise's chief engineer has turned into a crazed, psychotic serial killer, despite Scotty's denials. But after a telepathic probe reveals that the knife may somehow be connected to mysterious deaths that go back hundreds of years, Kirk surmises that there may be some kind of otherworldly or supernatural entity that feeds off terror and hijacks the bodies of unsuspecting bystanders to commit its ruthless murders. The episode may not win any awards for gender equality, but "Wolf in the Fold" earns its place as one of the most horrifying stories that "Star Trek" ever produced.

Some may consider "Identity Crisis" something of a filler episode for "Star Trek: The Next Generation." Set almost entirely within the confines of the Enterprise, it's a fairly standard TV bottle episode, but those descriptions don't do justice to how scary the story really is. Few will ever put it on their list of favorites, but it will make your skin crawl and have you fearful of every itch and uncomfortable sensation, wondering if it's the start of a deadly metamorphosis.

The episode opens with flashbacks to Chief Engineer Geordi LaForge's time as an ensign on the USS Victory, alongside crewmate Susanna Leijten, when they were investigating the disappearance of 49 Federation colonists on Tarchannen III. As we catch up with LaForge in the present he gets a visit from now-Lt. Commander Leijten. She arrives on the Enterprise with news that other members of their previous mission have abandoned Starfleet and attempted to return to Tarchannen III, and there's concern that whatever happened to those officers may happen to them next.

What happened to the other officers isn't a case of kidnapping, however. We soon learn that back on that mission years ago, the entire team was infected with an undetectable parasite and all of them — Geordi included — are slowly mutating into a bizarre, bioluminescent lifeform. At its best when delving into the creeepiest moments of body horror, "Identity Crisis" will get your adrenaline rising with elements of the best sci-fi thrillers.

When "Scientific Method" begins, Captain Janeway is feeling under the weather, to put it lightly. She's overworked, stressed out, and irritable, with splitting headaches that lead her to snap at her best friend, confidant, and security chief Tuvok. When Chakotay and Neelix fall ill next, the Doctor does some investigating and discovers a strange symbol microscopically printed like a barcode on the nucleotides in their DNA. When he tries to inform the captain, his program disappears.

As the mystery widens, Seven of Nine receives a secret message from the Doctor, who informs her that aliens have somehow invaded the ship and are somehow performing genetic mutations on the crew without their knowledge. When Seven adjusts her Borg implants to detect the aliens, we're shocked to discover that they're everywhere — invisible to the naked eye — and moving about the ship while torturing the Voyager crew with bizarre and dangerous experiments that leave multiple crewmembers dead. With the threat undetectable by conventional sensors, and seemingly impossible to thwart, Seven must find a way to alert Janeway — but to stop them they may have to do the unthinkable.

An episode that will have you cringing in horror, "Scientific Method" is essentially "Hostel" on a starship. While it's not as grisly or graphic, it's just as disturbing in its own way.

"Star Trek: Discovery" went for scares on more than one occasion, with Season 4's "Stormy Weather" arguably the best such episode to date. After its emergence in the 32nd century in Season 3, the recently-rechristened USS Discovery is on a mission to investigate a strange phenomenon labeled the Dark Matter Anomaly and a mysterious, non-humanoid race designated as Species 10-C.

As the episode opens, the Discovery embarks on a journey into a spacial rift left by the DMA. But once inside it's nothing like they expected, with no activity of any kind, as the region appears to be devoid of all matter and energy. But something must be there, because the ship is struck by increasingly dangerous malfunctions and the shields are quickly being drained. While Captain Saru wants to abort the mission, others want to stay as long as possible to get more information on the DMA, certain that there must be answers inside the rift.

As more calamities strike the ship and crew, it begins to feel like the rift is trying to kill them with a mind of its own. They may have to rely on the ship's newly self-aware artificial intelligence, Zora, if they are to have any hope of getting out alive. A story that ratchets the tension up like a wrench, this entry's ticking clock and deepening mystery will make it hard to keep your head above the blankets.

If you're looking for a different take on a monster movie — a truly sci-fi spin — look no further than the original "Star Trek" series episode "The Doomsday Machine." Essentially "Jaws" and "Moby Dick" in outer space, the episode sees the Enterprise responding to a distress signal from the USS Constellation, which they discover and heavily damaged and adrift in the remains of a destroyed solar system. The only living soul aboard is Commodore Matt Decker, whose mental state has deteriorated as a result of whatever deadly incident occurred there.

The traumatized Decker tells Captain Kirk that the crew of his ship was killed by a mysterious, massive machine when they tried to escape its attack. It seems the device is capable of destroying entire planets for fuel, with untold trillions of lives at stake in its projected path through the galaxy. With Kirk temporarily stranded on the Constellation, the planet killer arrives on the scene and fires on the Enterprise. A desperate, guilt-ridden Decker hijacks command from Spock, trying to draw the machine into a pitched battle that the starship can't possibly win. Not frightening in the conventional sense, "The Doomsday Machine" is nevertheless one of the original series' most suspenseful and unsettling episodes.

The third and final season of "Star Trek: Picard" was nothing less than a full reunion of the cast of "Star Trek: The Next Generation." But perhaps the most franchise-shattering storyline involved the revelation that Picard had a son he never knew in the form of Jack Crusher, whose mother — Enterprise chief medical officer and Picard's sometime lover Dr. Crusher — had kept him hidden from his father for more than 20 years. When the father and son finally unite, we learn that Jack may have a dark secret that even he isn't aware of, and "Vox" unveils his hidden history with a splash of horror.

It turns out that Jack isn't just the son of Picard and Dr. Crusher. That's because he's inherited whatever was left in Picard during his time as Locutus — the twisted, villainous Borg leader he'd become in the epic "TNG" two-parter, "The Best of Both Worlds." Not only does Jack have Borg within him, but that Borg element has given him a sinister connection to the Borg Queen. It also gives him incredible abilities that turn him from a maverick adventurer into a Borg weapon that could assimilate the entire Federation into the Borg collective. Dark and foreboding, "Vox" depicts Jack as a nearly werewolf-like monster who can go from do-gooding renegade to insidious alien madman without warning.