There are different types of scary on Star Trek: there's jump-out-of-your-skin scary, the kind that comes with aliens who prey on the crew, officers who turn into spiders, or zombie Vulcans with vendettas. Then there's the more high-concept scary, where evil forces take over one of our favorite characters' bodies, or an alien invades the crew's dreams, making them afraid to go to sleep. The original list was so long that we had to remove some good ones, like "Remember Me," where everyone Beverly Crusher knows starts disappearing from people's memories, or "Voices," when Deep Space Nine's Miles O'Brien discovers there's a conspiracy against him and everyone he knows appears to be part of it. If having your sense of reality shattered doesn't give you a scare, you're made of pretty strong stuff.
Star Trek has also given us good old-fashioned murder mysteries like "Wolf in the Fold" (where the spirit of Jack the Ripper is on the loose), or monster-of-the-week episodes like "The Man Trap." But there's a reason those got bumped to make room for the rest, so read on, and see which ones we think are the 17 Most Terrifying Episodes Of Star Trek.
17 Catspaw (The Original Series)
Sure, this one is a little silly. It's a dressed-up Halloween episode, complete with eerie fog, witches, a dead crew member who speaks with someone else's voice coming out of his rigid body, and couple of aliens who have the ability to read minds, and kill with the power of their thoughts.
The stakes are high, as they have what appear to be "magical" powers. They manipulate matter, find a way to control the minds and wills of Scotty, Sulu, and eventually McCoy, and they can even affect the Enterprise up in orbit. Sylvia, rapturously played by Antoinette Bower, dangles a chain with the Enterprise on it, and by holding it over a flame, she can increase real ship's hull temperature to lethal levels.
But most of the fun in this one comes from chained-up skeletons, dungeons, black cats, and those ghostly witches at the beginning, that take turns howling at Kirk, Spock, and McCoy.
“Wind shall rise ... And fog descend ... So leave here, all, or meet your end.”
Spock is unimpressed. His analysis? "Very bad poetry, Captain."
16 Darkling (Voyager)
The Doctor becomes a menace in this Voyager episode, and does it with panache; you can tell that Robert Picardo dug in deep. The Doctor's been fooling around with his personality program, and some nasties have taken over, making him into a sadist of the scariest kind.
First, he slips down to the planet's surface, almost kills Kes' new boyfriend, then pushes someone's else's hand into a fire. Back on the ship, he's his old self. But B'Elanna knows there's something up with his subroutines, and next thing we know, she's lying unconscious on the floor. The Doctor tells Tuvok it's because of a bad salad (yes, a bad salad), but we know better.
The most fear-inducing moment comes when he deliberately paralyzes B'Elanna from the waist down, rendering her completely helpless. His plans for her include making it impossible for her to pass out no matter how much pain he inflicts, a plan he gleefully describes while she lies there, paralyzed.
15 Conspiracy (The Next Generation)
"Conspiracy" was a first season TNG episode, which means the show was still getting its sea legs, but it works: an old friend of Picard's alerts him to a conspiracy at Starfleet's highest levels, then gets killed, so the Enterprise heads to Earth to see how far the infiltration has gone.
Then they start adding in the horror movie goodness. Admiral Quinn brings a weird alien bug to the ship, in hopes of infecting Riker; turns out Quinn has a weird little wiggling spike in his neck that shows he's been taken over by an evil parasite. Picard is forced to attend to a dinner where the main course is a bowl of raw, squiggling mealworms. He and Riker follow another bug—this one with a Ray Harryhausen-style scuttle—to its host officer, Remmick, and it craws into his voluntarily open mouth. And then Remmick's neck starts pulsing. Gross! They shoot him, and a slimy, shrieking creature pops out of his ribcage, Alien-style. They shoot again, this time to kill.
The final touch? Remmick sent out a homing beacon right before they killed him. Cue the music ... along with the response we hear emanating from a distant galaxy.
14 Macrocosm (VOY)
"It's almost as if they dropped what they were doing and ran," Neelix says, when he and Janeway return from an away mission to find sections of the ship completely abandoned. Next, they hear a strange humming sound coming from a unseen creature, which punches its way through a floor panel and leaves a pile of icky mucous behind, complete with "fragments of non-humanoid DNA." And so it begins.
Systems are shutting down, and eventually it's up to vigilante Janeway, in her tank top, phaser rifle, profuse sweat, and yes, KNIFE, to go after the creatures, which are actually macroviruses grown to massive proportions. Thanks to their size, they're now able to physically attack as well as infect. Also, they're disgusting. Also, they've already gotten to the crew, who are mostly unconscious with creepy growths on their necks that tiny bugs fly out of. Then there's also that part where Neelix screams and disappears.
Badass Janeway takes over, and saves the ship, but not before engaging in hand-to-hand combat with a giant, slimy, tentacled virus-creature. Good times.
13 Distant Voices (Deep Space Nine)
It's hard to make an episode happen almost entirely inside a character's mind and still be intense and scary, but "Distant Voices" pulls it off.
A pissed off alien attacks Dr. Bashir telepathically, and we see Bashir's battle for his sanity—and his life—play out on the abandoned decks of the space station. He starts hearing voices; and rapidly aging. He gets older and weaker as he makes his way to sickbay, watching tragedies befall his friends: Dax gets dragged away by an alien, Sisko gets pulled through a bulkhead, Odo is stuck in a half-liquid state, with all of this signifying the deterioration of Bashir's mind.
Now since it's Bashir, things take a narcissistic turn as he keeps speculating on what aspect of his personality each of his friends represents, but it's still spooky, especially when he finally gets to Sickbay, old and doddering, and finds his vengeance-seeking adversary there waiting for him.
12 The Haunting of Deck 12 (VOY)
Neelix tells a ghost story, and it's a good one. We're in season six, when Voyager is carrying four ex-Borg children as passengers. The ship needs to power down completely for a few hours, which includes the children's regeneration chambers, so Neelix is sent to keep them company. When he starts his spooky tale, about an alien invasion of the ship that nearly destroyed the ship, they ask: is this about Deck 12? Because they heard it was haunted.
Neelix tells them about the entity that was accidentally brought on board and started causing ship-wide malfunctions. The crew couldn't contact each other, systems stopped working. Then the entity started trying to hurt them, nearly asphyxiating Seven of Nine and electrocuting Tom Paris. We flip back and forth between the events that led to the power shutdown and the kids reacting to Neelix telling them about it. It's a great combination of good old-fashioned ghost story (told around emergency flashlights instead of a campfire), and a true-to-the-genre Trek story about a seemingly malevolent alien who isn't what it seems.
11 The Best of Both Worlds, Part 1 (TNG)
If you ever watched the first season of 24, you'll remember why it was so intense: the risks and the consequences were simultaneously global and deeply personal. The same double whammy comes in what's definitely the best end-of-season cliffhanger in the history of the franchise, and probably among the top five best in TV: Picard gets abducted by the Borg. The threat couldn't have been bigger: Picard, the Enterprise, the Alpha Quadrant, the galaxy. Earth. Everybody's fate hung in the balance, as the Borg moved closer to Earth, and began their attack.
The Borg are already terror-inducing, and in this episode, they invade the alpha quadrant with their giant cubed ship and their relentless, ominous theme music. They abduct Picard, and then up the stakes even more: the Enterprise crew looks up to the viewscreen to see their former Captain transformed. "I am Locutus of Borg," he tells them, a Borgian echo in his voice, an implant covering part of his face. "Resistance is futile. Your life as it has been is over. From this time forward, you will service us."
Riker gives Worf the order to fire, and the screen goes blank.
Longest. Summer. Ever.
10 The Thaw (VOY)
The normally amusing Michael McKean (This Is Spinal Tap) guest stars in this deeply unsettling Voyager episode that plays into both childhood nightmares and the universal fear of clowns. This isn't your typical dream episode, where someone wakes up and it's over; in this nightmare, the threat of death loom large.
Three aliens have been held captive in a collective bad dream by McKean's scary clown for 19 years, forced to live in his nightmarish world of circus freaks under the ever-present threat that he can do anything he wants to them and it will look, smell, sound, and feel completely real—so real, in fact, that he's killed two of their companions by inducing heart attacks, brought on by fear. The clown, it turns out, is fear itself.
Harry Kim gets trapped in there and we feel his terror as the clown exploits his deepest fears and the rest of the freaks revel in it. The fun of terrorizing their victims is what makes this especially frightening, given that their plan is to keep doing so forever. We recommend avoiding this one right before bedtime.
9 Frame of Mind (TNG)
Normally the episodes where our crew puts on a play can be a little trying, but this one uses the drama of the play, in which Riker plays a character who's losing his grip on reality, to enhance the story in which, yes, Riker is losing his grip on reality. Or is he? Throughout the episode, we can't tell if the scenes on the Enterprise are the real ones or the scenes in the alien psychiatric institution are where it's all going down. Riker keeps switching back and forth, from being a patient locked up at the Tilonus Institude for Mental Disorders to being on the ship and having nightmares about it. In both places, there's an alien who keeps appearing, triggering more paranoia from Riker and making him doubt his sanity in either place. Which is the nightmare? Which is real? It keeps us guessing from scene to scene as Riker—in a terrific performance by Jonathan Frakes, who doesn't usually get such rich material to work with—slowly unravels.
8 Scientific Method (VOY)
This is a great Voyager episode, full of scary moments that draw strong performances out of its cast, particularly Kate Mulgrew, Jeri Ryan, and Robert Picardo.
Aliens nobody can see are all over Voyager, doing scientific experiments on the crew. Neelix and Chakotay are being transformed into other species, others are dying, and nobody knows why. The Doctor, in hiding in the holodeck, gives Seven of Nine the ability to detect them (albeit with a creepy greenish glow) by adjusting her ocular implant. Then poor Seven has to walk around, seeing the aliens but pretending she can't, even when one of them walks right up and sticks a pointy probe in her.
There's this especially horrifying moment when she races in to tell Janeway they've been invaded, and stops in mid-sentence because she sees two aliens on either side of her Captain, adjusting spikes on both sides of her head. Janeway's been experiencing headaches like a motherf*****, because they've been secretly increasing her dopamine levels to see just how much pressure she can take, and we feel every bit of it.
7 Impulse (Enterprise)
Two words: zombie Vulcans.
This episode was even shot like a horror movie, with tilted angles and dramatic lighting. Four members of the crew board a disabled Vulcan ship, and their rescue mission turns into a fight for survival as they are chased around by mobs of relentless zombie Vulcans. Exposure to a new power source has not only removed their emotional control, but turned them into mindless homicidal thugs with disfigured faces. T'Pol starts to feel the effects, and we watch her slowly lose her grip and edge towards violence, while the crew dodges their enemies and keeps a nervous eye on her.
Oh yeah: apparently there's no such thing as zombies in the future, because at no time does anyone in the landing party ever use the word. If Voyager's Tom Paris were there, you know he'd be calling it like it is, and he'd have ideas about how to fight them, too.
"Something has happened to the Vulcans," Archer tells the Enterprise, and by that time you're practically shouting at the TV. "They've turned into zombies! Don't you watch The Walking Dead?"
6 The Assignment (DS9)
The only thing scarier than someone holding your wife hostage is someone holding your wife's body hostage by living inside it. Keiko returns from a trip and informs her pining husband that she's an alien who has taken over Keiko's body, and if he doesn't do exactly what she says, she'll kill her. To make it worse, he has to pretend that everything's okay, which means he has to live with her AND let her be with their daughter, Molly. Every time Keiko has her hands on Molly's shoulders, we recoil on his behalf, as he's the only one who knows she's an evil stranger and he must keep the secret or risk her death.
The alien is a Pah-wraith whose goal is to kill the Prophets, and it'll do whatever's necessary to Keiko to make sure nothing goes wrong; it cruelly demonstrates this by hurling Keiko's body off the upper deck of the station. In Sickbay, as she's "recovering," it threatens O'Brien with the loss of his wife and daughter, reminding him to obey. There's an anxiety-inducing edge to every scene in this one, as O'Brien fights to save his station and his family at the same time. Alone.
5 Night Terrors (TNG)
The Enterprise crew finds a lost ship with one sole survivor: a catatonic Betazoid. The rest of the crew has been murdered, and while they try to solve the mystery, they find themselves trapped inside a space-time anomaly and see the warning signs among their own people... whatever happened to that ship is about to happen to them.
Troi keeps having nightmares--weird floaty ones that reek of 1990s VFX budgets--but the rest of the crew can't dream at all, and it's making them slowly go insane. Paranoia runs rampant, and so do hallucinations. Picard thinks the turbolift is collapsing on him, Riker feels like someone's in his quarters watching him, and Worf even tries to commit suicide because he's lost his ability to conquer his fear.
Crusher gets the spookiest moment of all, when she's in a room with the corpses from the first ship. Suddenly, all the dead bodies around her are sitting bolt upright, and she's completely alone with them, not sure if it's reality or her own mind tormenting her. It'll give you the shivers for sure.
4 The Cage (TOS)
This was the original Star Trek, the first pilot done, before Captain Kirk came along. It's a great story with a pretty terrifying group of aliens; not only do they have oversized bald heads with pulsing veins, they ALSO have the ability to read minds, and then plant any image they want in there, and even complete experiences, making you think that you are living through exactly what they want you to go through.
That's all fun and games when it's a picnic with horses, but when Captain Pike misbehaves, they make it clear that he should probably try to avoid "the unpleasant alternative of punishment." Next thing you he's on fire, surrounded by flames, with something horrible (and presumably flammable) dripping from his sleeves.
They can make the crew think anything they want, which puts them all in a danger they can't possibly protect themselves against. "With illusion they can make your crew work the wrong controls or push any button it takes to destroy your ship," Pike is warned. That's even scarier than the fire.
3 Genesis (TNG)
This one will actually make you jump. Data and Picard leave on a quick away mission, and while they're gone, strange things start happening to the crew. Troi can't tolerate the temperature anymore, Worf is getting edgy and violent, La Forge can't focus on anything and Barclay seems hopped up on caffeine.
Things get worse. Troi takes a bath in her uniform, and Worf rages in, and bites her on the cheek. When Dr. Crusher examines him, he sprays her face with venom.
Picard and Data return to find the ship adrift, and discover, slowly, that the crew has been de-evolving. Worf's on the loose, Riker's a big hairy primate, and Barclay scares the crap out of an increasingly jittery Picard by popping up in engineering as a half-mutated spider. Barclay's spider is truly freakish, but Data tells Picard that the reason he's so terrified is because he, too, is de-evolving. It's a race against time, as well as against a rampaging Worf, as Data tries to cure the crew before they all kill each other.
2 Empok Nor (DS9)
This one has all the right ingredients for a late-night scare. You’ve got an abandoned space station (Empok Nor), recently-occupied-but-now-empty stasis pods, vengeful no-longer-in-stasis Cardassians, crew members being picked off one by one, and an increasingly homicidal Garak. That plus power failures, equipment issues, and a blown-up runabout (which cuts off their escape) make for a typical survival-in-a-haunted-space-station story that will have you looking over your shoulder.
Poor Garak doesn't mean to be homicidal, but he has no defense against the psychotropic drug that's already turned the other Cardassians into dangerous enemies. He manages to kill them off, but then the drug starts to work on him too, and he kills the last of the four crew members who aren't part of our regular cast. (You don't need to wear a red shirt to become one.) Once recovered, Garak is filled with painful regret, but even with remorse, his relationship with Nog, who was along on the journey, will never be the same.
1 Schisms (TNG)
This comes in at #1, because it's one of the scariest concepts ever: aliens are abducting Enterprise crew members at night and doing experiments on them with painful pointy things. It's exactly what every six-year-old is afraid of, really... getting sucked out of your bed in the middle of the night so terrifying hooded beings can poke at you.
This episode works particularly we'll because of how it unfolds. We find out what's happening one small step at a time: there's something wrong with Riker's sleep, Worf gets freaked out by a pair of barber's scissors, suddenly there are multiple crew members reporting irrational fears and Troi puts it all together and gathers them in the holodeck to see if their experience is as shared as it seems.
They take turns describing it until they've recreated it together: a dark room, an examination table, a restraining arm, and those sharp, intrusive instruments. Not only that, there are hooded creatures who make strange, ominous clicking sounds. It's the creepiest one ever, and sure to feed some existing nightmare from deep in your psyche.
The newest show in the Star Trek franchise is Star Trek: Discovery, scheduled for a premiere in May 2017.