Star Trek was Gene Roddenberry’s hopeful ideal for humanity’s future, as well as an exploration of what it is that makes us human—flaws and all. While most episodes do explore an optimistic future where all human war, disease, and suffering have been eradicated, there is still more to Trek than solvable problems.
But it's not all just Tribbles and hot green women either. There are all those anomalies that clone ships and give you leprosy, and aliens with Play-Doh on their heads who want you dead for not worshipping their gods who are made of jelly. Roddenberry himself didn’t want his human characters to necessarily be capable of bad things—believing we will have evolved past it by the time Star Trek happens—but that undermines the honest exploration of the human soul that the franchise has often been lauded for. So sometimes, the franchise got dark. Very dark. So put on a pot of Prozac, because here are the 15 Darkest Episodes Of Star Trek, Ranked.
15 The Darkness and the Light (DS9)
Kira Nerys had no qualms about her past as a terrorist who fought for her freedom against the Cardassian occupation of her planet. She killed collaborators, she sabotaged machinery, and bombed facilities. Years later, someone starts killing people in her old resistance cell. By then, she’s a surrogate mother and eight months pregnant. The assassin, Silaran, was a Cardassian laundry worker who'd been caught up in one of the explosions Kira masterminded. It left him scarred and crippled, though many others, including women and children, were killed.
This episode deals with Kira’s terrorist past in a guttural and real way, showing consequences with an unflinching gaze. Just because the Bajorans were right to fight back against their oppressors doesn’t dispel all the bad things Kira did during the Occupation. Silaran, too, has a point, but is also hardly on the moral high ground. Their debate makes up much of the final act. They make their cases to each other, with neither of them apologetically defending their actions, and that’s what makes it so brutal. They understand what they’ve done is wrong in the general sense, but they feel no compunction for it. After all, it was war.
Of course, if you’re feeling bad, the next episode is “The Begotten,” which is also depressing. Because this is Deep Space Nine.
14 Dear Doctor (ENT)
On the surface, “Dear Doctor” looks like a typical medical mystery episode that also lays the groundwork for the creation of the Prime Directive. What actually happens is this: Captain Archer and Doctor Phlox—our series' heroes—commit genocide.
A species called the Valakians will be extinct within two centuries due to a disease. Archer declines to give this species warp technology which would help them reach other species who may have a cure, as he’s uncomfortable with sharing dangerous tech with a less advanced race. Then, regardless of his apparent inability to grasp how genetic diseases work, Phlox finds a cure, but doesn’t want to share it.
Phlox believes it would be interrupting a natural evolutionary development, which would make sense if it wasn’t entirely wrong. Evolution exists to keep a species from extinction, not accelerate it. After a minor debate, Archer agrees that the moral thing to do is not save the dying race because they are genetically inferior. Sorry, fellas!
13 The Paradise Syndrome (TOS)
When an episode of Star Trek begins, you can be sure of a few things. Captain Kirk will punch or have sex with someone. Sometimes both, but in which order, no one can say. Stranded on a planet of alien Native Americans (you make do with the costumes you have) for almost three months, an amnesiac Kirk is taken in by the natives and falls in love with Miramanee, who soon becomes pregnant.
Meanwhile, Spock becomes darkly obsessed with finding a way to save the captain before an asteroid destroys the planet he's stranded on. He isolates each member of the crew and refuses sleep for weeks on end in order to save his friend from something he believes is his fault. Their friendship has never been more clearly displayed than where Spock’s cold demeanor actually is an emotional reaction. The Enterprise saves the day (sorta), but in the process, Miramanee dies. Kirk says a sad and quiet goodbye to the life he wishes he still had.
Admittedly, even with the usual campiness to go along with the episode, it’s a tough viewing. However, if you give it a chance, you’ll get to hear the creative pronunciations of “Shangri-La” and “life form,” and thrill in Shatner’s joining ceremony dance. Isn’t that why we all watch Star Trek in the first place?
12 Homefront/Paradise Lost (DS9)
This two-parter asks the age-old question of freedom vs. security, one that has never been more relevant than it is today. From the paranoia that comes with the knowledge that the true enemy can be just about anyone, to the lame duck leadership unprepared to handle the threat, it’s as if these episodes were filmed just last week.
What’s most frightening is Starfleet’s handling of the terrorist attack on Earth. A group of officers intend to launch a coup and take power. They do so by causing blackouts under the guise of Changeling infiltration, and establish martial law. The audience is indicted in all this as well; we’re made to agree with all the new security measures: checkpoints, blood screenings, and soldiers on every corner, until the conspiracy is revealed by Jesse Ventura and Alex Jones
Sisko and Odo who had also been taken up by all the paranoia.
This makes Starfleet less perfect, and their paradise a little darker. This was Deep Space Nine’s theme: question Star Trek the way the franchise would question other concepts, and in this exploration, we see the alluring comfort of fascism and the great failures of those who allow it the chance to thrive.
11 Necessary Evil (DS9)
"Necessary Evil" is a noir story with snappy Raymond Chandler dialogue, chiaroscuro lighting, dangerous men, and bad women. The center of the story is Odo’s reinvestigation of an unsolved murder, though it branches out into character backstories that provide insight into the relationships that drive it forward. The end result finds everyone involved in the case guilty of something, and the series finally crosses a long-awaited threshold.
Kira Nerys is the female lead in the series, and, until a year before these events, she was, by her own admission, a terrorist fighting the Cardassian occupation of her people. Kira was even considered to have been the victim's mistress, but the truth is much darker.
While Kira did have an alibi that night, she did still kill the man, and he was a collaborator. And she kept that from Odo for years. The revelation sits between the two awkwardly. The morally certain Odo defies his beliefs and decides to keep the truth hidden, protecting Kira because of their friendship. Kira says her only regret is not telling him earlier. It’s not the murder that drives a wedge between them, but the lies.
10 Balance of Terror (TOS)
The usual lighthearted camp that permeates The Original Series is absent here. The Enterprise is caught in a pitched battle against a Romulan ship. If the Romulans get away, they’ll have information on Starfleet defense's weaknesses; if the Enterprise gets away, they’ll have information on cloaking devices and plasma torpedoes. Neither captain wants to get away, either. They both have information that, if taken back to their superiors, can result in all-out war. They don’t want that, but they are bound by duty to their governments and to their crew. So they fight miserably.
The tension is raised when we learn that Romulans and Vulcans share a common ancestry. This leads to questions of Spock’s loyalty, an exploration of the stress long-term soldiers experience during war, and the desire to avenge the losses resulting from that war. It highlights the cyclicality of violence—the ultimate eye for an eye.
The fight is clever and full of tension, and the themes of the episode are fully developed. The ending is bleak and quiet. It may wrap up in a somewhat predictable manner, with the Romulans destroyed, but because the two sides don't communicate with each other, so is the chance for true peace.
9 Man of the People (TNG)
Deanna Troi’s episodes are nearly universally terrible. This one isn’t. It’s simply unpleasant. Alien ambassador Alkar seduces women, fosters dependence, and makes them psychic receptacles for his dark emotions. Once purged of them, he can function unburdened and level-headed, and do his job better. He cares for them to the extent that he can use them. Once one dies, he hungrily and immediately finds another to use, or else all those dark feelings start to flood back. Meanwhile, his victims devolve into psychosis and age rapidly, eventually looking like the old woman in the bathtub from The Shining.
Sexual assault is rarely explored on Star Trek (studio rules), but “Man of the People” works around the limitations by adding the psychic layer to it and focusing on the aftermath in the metaphorical sense: with the victims forever changed and the event following them to the grave. By making Alkar a powerful diplomat, it also explores the comparative helplessness victims feel and the sense of power the assailant does.
Dr. Crusher is able to save Troi, and in doing so, all of Alkar’s dark emotions—everything he’s done to all these women over the course of decades—comes back to him all at once. He dies quickly but painfully, his mind filled with the horror of what he’s done.
8 Sarek (TNG)
The darkness of this episode doesn’t come from any sci-fi tropes or crazy alien wars. It comes from the honest exploration of old age. Sarek, Spock’s father, shows up to host a peace conference that would be the high watermark of an already legendary diplomatic career. The only problem—besides being old and still stuck with that awful Vulcan haircut—is that he has Bendii Syndrome. It’s a degenerative neural disorder Vulcans and Romulans are prone to, comparative to Alzheimer’s, Lewy Body, Parkinson’s and Huntington’s. His Vulcan attaché has been covering for him, but the change in Sarek is noticeable. He’s emotional, unpredictable, and disoriented.
In a normal episode, this would be a medical drama—racing against the clock to find a cure and save the day—but it’s not broached here. There is no cure. Through a mind meld with Picard, we see an uninterrupted stream of the turmoil Sarek’s mind is under. The deterioration and volatile nature of Bendii Syndrome is personified in Picard in an intense display of shifting moods and reactions, and eventually devolving into a complete untethering from reality.
In the end, they’re able to help Sarek put the final exclamation point on his career, but the disease will progress, indignity by indignity, until the end.
7 Remember (VOY)
Voyager had a number of problems during its seven-year run, and though “Remember” doesn’t often make best-of lists, it’s certainly one of the finest episodes produced in the series. Through psychic flashbacks, B'elanna Torres experiences the early life of a psychic named Korenna. It’s essentially a look at what would happen if an SS guard fell in love with a Jew in a world where the Nazis won and hid the history of what they’d done.
The desperation and fear the Regressives feel as they’re being transported to a new home is chilling in its allegory to the trains to concentration camps and the gas chambers. That we actually see some of them burned to death diminishes the subtlety, but that’s part of the point. The episode is stark, brutal, and unflinching. Voyager discards this in order to be memorable, drawing parallels to Korenna’s own desire for the sins of the past to be remembered.
At its heart, the episode isn’t about complacency or forgiveness, it’s about responsibility and the importance of history: asking questions, confronting the story, and accepting the truth so that it could never happen again. The script and the acting comes from an emotional and urgent place. There’s no Trek sanctimony or easy answer. These things happened. There are consequences that we all have to live with.
6 Course: Oblivion (VOY)
Of all the episodes on this list, this one is the most rewatchable because you get to watch Neelix die in writhing pain every time you do. Unfortunately, it’s not the real one—nobody in this episode of Voyager is real. They’re the biomimetic (like Velcro!) duplicates from a previous episode. These Velcro people believed they are real, and even created a copy of Voyager, which is now breaking down because their warp core is killing them. (Look, Voyager is the same show that believed you could break a black hole by shooting it. Science isn’t its strong suit, just go with it this time.)
Slowly, the characters start dying off, coming to accept that while they weren’t the originals, they had unique experiences. Their last hope is to launch a probe filled with personal logs. They won’t live—but then again, who does?—so they can at least be remembered.
Only they aren’t. The probe doesn’t launch, and the entire ship explodes into some kind of snot before anything can happen. Admittedly bleak, the episode explores concepts of identity, sentience, and legacy with a grim pragmatism that’s rare for Voyager, and even for Star Trek. as a whole.
5 The Siege of AR-558 (DS9)
Star Trek doesn’t care much for war, but they do use it often enough. Here, our heroes meet with a bunch of Gold Shirts (who are all going to definitely survive this episode, definitely) who have been stationed on AR-558 for over a year. Unfortunately, the Jem’Hadar—a group of genetically engineered super-soldiers so dangerous they have to be constantly pumped with alien heroin to keep them calm—want to take the place back.
The enlightened and kinder humans of the Roddenberry mold are no longer perfect. The bubble they lived in has burst, and they’re pushed to the brink. All of the Gold Shirts have been here a while, each traumatized and exhausted. Some have gone native, collecting trophies from their kills; others are on the cusp of a nervous breakdown. The line between right and wrong has long since faded. Even Captain Sisko no longer has qualms about turning an enemy’s own “immoral” weapons against them.
War is shown as something vulgar, even when it’s necessary. There’s no glory in it. Once you’ve experienced it, you come back broken or changed, if you even come back at all. In the end, almost all of the Gold Shirts are killed (surprise!) and replaced with new, younger officers about to go through the same thing all over again.
Oh, and Nog’s leg gets blown off.
4 Chain of Command (TNG)
With the narrative focused on Picard’s internment under the ghoulish yet strangely warm Gul Madred, we’re given full measure of the degradation and dehumanization involved in the practice of torture. From being stripped of his clothes, to being kept in a stress position and deprived of food and sleep, to the use of misinformation and desired submission, “Chain of Command” keeps the audience aware of the effects of torture, and its actual lack of efficacy.
Madred is both Picard’s savior and endangerer. A codependent relationship is fostered through the physical and psychological games that eventually damages both men. For Madred, his agency is lost when Picard no longer fears him, instead seeing him as the scared young boy growing up homeless on a broken planet. All Picard has to do is look at the four spotlights above and tell Madred there are five lights. He just has to repeat the lie and the pain would stop. He’s rescued before he can answer, but, as he revealed to Counselor Troi later, he truly believed he saw five lights in the end.
Madred may not have gotten Picard to divulge state secrets, but he did win. Picard broke. The entire episode is a real laugh riot.
3 The Drumhead (TNG)
“The Drumhead” is more of a televised play than an episode of Star Trek. Like several entries on this list, it’s timeless in its exploration of militancy and fanaticism.
Starfleet special investigator Norah Satie comes aboard the Enterprise to investigate a potential sabotage, which she believes was caused by a mole. Worf wants to find the traitor on the ship to prove his own loyalty; he’s currently considered a traitor amongst his own people and is desperate to prove his worth to Starfleet, the only family he has left.
They come to a crew member named Simon Tarses, who is revealed to have hidden his quarter-Romulan bloodline from Starfleet. Immediately thought to be guilty, Satie schedules a hearing, merely for, as Picard says, “having the blood of a current enemy.” Not so long ago, it would have been Worf in the hot-seat, being questioned for having the blood of a then-current enemy. When Picard defends his subordinate, claiming this is a drumhead trial (hey, that’s the title!), Satie investigates Picard as well. In the end, Picard successfully defends himself and Satie is invalidated, but Tarses’ career has been ruined.
Tackling themes of racism, xenophobia and the dangers of limiting speech, thought, and civil liberties, “The Drumhead” is so high on this list because it can happen anywhere at any time. Hell, it may be happening now.
2 In the Pale Moonlight (DS9)
The title of this episode is a Batman reference, so of course it's going to be dark. Billions are dying during the Dominion War. The only way to win is to get the Romulans involved. So, Sisko fakes evidence to prove the Dominion is planning on breaking their non-aggression pact. Then he lies, covers up crimes, bribes, and has people killed in order to keep the truth from being revealed. In the end, he succeeds. Thousands of Romulans will die, but the Dominion will be defeated.
Over the course of the episode, as Sisko reveals to us everything that happens, more of his uniform is stripped off. It works symbolically in that he’s bearing his soul to us and acting less and less like a Starfleet officer should. He discusses his crimes, before gravely and sadly admitting that he could live with it.
This never would have happened under Gene Roddenberry. Never would a human character—let alone a protagonist—be allowed to do these things. It shows, however, that there is a cost for freedom; it shows that Ben Sisko is willing to abandon all his principles so that the good people of the Federation can remain innocent and ignorant of the price of their utopia.
1 Duet (DS9)
When Star Trek is at its best, it’s able to deftly take a concept and turn it on its head. It does so in “Duet,” which is arguably the finest episode the franchise produced despite nobody actually singing.
For fifty years, the Cardassians ruled the Bajorans through brutality. Just a few years after the Occupation ended, a man comes forward claiming to be the Cardassian war criminal Gul Darhe'el (think Amon Göth). Kira Nerys, a Bajoran, is already preparing the firing squad, but the truth of the matter is much darker. This man isn’t Darhe’el; the real one died peacefully in his sleep and was treated as a hero on Cardassia.
This man is Aamin Marritza, Darhe’el’s former file clerk driven mad by guilt. He watched Darhe’el commit atrocities at the Gallitep camp for years and did nothing. Kira has to defend this man, and confront her own racism against Cardassians. Trek turned the “Just following orders” defense around, and asked a larger, unconsidered question. Marritza was a collaborator, but what could have he done? He was just one man surrounded by thousands of soldiers.
Despite the truth being revealed, an angry Bajoran kills the clerk.
“He’s a Cardassian. That’s reason enough,” he says.
“No,” Kira realizes. “It’s not."
What are your favorite Trek episodes? Let us know in the comments! Want more Star Trek, but less depression? Take a walk on the lighter side with our list of the franchise’s most optimistic episodes.