Ragnarok-Proofing: In "The Sword of Kahless", they encounter ancient ruins of a civilization that died out centuries ago. The ruins still have working forcefield generators and security authentication systems to let the right people in.
Ragtag Bunch of Misfits: Most of the main cast. Sisko was looking for a quiet retirement (good luck), Kira was shunted into her role for disagreeing with the provisional government, Quark had to be blackmailed to stick around, Odo had no idea of his own origins, and Garak was a relic of the occupation with nowhere else to go. Bashir talked a good game about being a Frontier Doctor, but had secrets of his own. Nog was the first Ferengi in Starfleet. O'Brien was a family man, which makes him unusual for a main character on a Star Trek series (Star Trek characters tend to have more tragic family backgrounds IE Tash Yar, Worf, etc), but it's suggested that his promotion was contingent on remaining on DS9.
O'Brien:[Simpering voice] "Fix the replicators, Chief! "My console's offline, Chief!" I should've transferred to a cargo drone. No people, no complaints.
Nana Visitor got pregnant during filming for season 4/5 and the producers decided to integrate her condition into the storyline instead of trying to hide it, leading to Keiko being injured and the baby being transplanted into Kira's body to finish its gestation. Turns into a meta Crowning Moment of Funny when she blames Bashir for her being in that position, because he performed the transplant—Alexander Siddig, who portrayed Bashir, was the baby's real life father.
Additionally, a combination of contract issues and simple "show fatigue" made Terry Farrell want to move on from the show at the end of season six, leading to Jadzia getting killed. This is something the head writing and directoral staff didn't even want to do (Ira Stephen Behr straight-up said "I didn't want to kill Jadzia; to me, that had very little to do with good storytelling") but they felt they had little choice. (Luckily for them, Farrell played a member of a race that can pull off The Nth Doctor relatively easily.)
Real World Episode: "Far Beyond the Stars", where Sisko wakes up as a Science Fiction writer in the 1950's, and Deep Space Nine is just a story he's been writing. Of course no one wants to read a story where a black man commands a space station...
Rearrange the Song: The opening credits and main title theme were modified between seasons 3 and 4.
Quark: Have I ever told you how much I hate that smug, superior attitude of yours? Odo: Have I ever told you how much I hate your endless lying, your pathetic greed, your idiotic little schemes? [...] Well, that's fine with me...'cause I hate you, too. You're nothing but a petty thief!
Recurring Character: Lots of them. The fixed location of the station meant that quirky aliens would need to come to them, not the other way around.
The Ferengi were rebuilt into a more robust fictional society, and the innate contradictions in their culture were acknowledged and addressed on their own terms over the course of the show. For example, their subjugation of women was ended in order to gain new workers and an expanded consumer base instead of for ethical reasons.
It also spent a lot of time exploring what the characters of a utopian society like the Federation would really do if they were faced with having to resort to morally ambiguous or even plain deplorable means (e.g. "In the Pale Moonlight") to rescue that society in an all-out war against The Empire. Everyone is portrayed as a shade of gray, until Sisko and the Cardassian war criminal Gul Dukat confront each other in "Waltz" and Dukat realizes he should have fulfilled his dreams of total genocide on Bajor after all. Even a Gray and Gray Morality setting can still have genuinely evil characters.
"Starship Down" was an attempt to do Das Boot in a gas giant, with Jem'Hadar as the enemy destroyers.
The maligned episode "Meridian" was described by writer Ira Steven Behr as Brigadoon...IN SPACE. He subsequently said of the idea, "I am a moron."
The entire Dominion War is World War IIIN SPACE. The Federation is Great Britain/the US; the Dominion is Nazi Germany/Imperial Japan; the Klingons and Romulans take turns with different aspects of the USSR; Cardassia is both Fascist Italy and Vichy France (with a greater emphasis on Vichy France toward the end); the Female Changeling and Weyoun are Hitler, with the Changelings as a whole also taking on aspects of the Japanese Emperor; Dukat is a combination of Mussolini and Petain, with a bit of Hitler mixed in; Damar is de Gaulle; the morphogenic virus is the atomic bomb; and the extermination of Cardassians is a combination of the order (never implemented) to raze Paris and the infamous Nero Decree.
Red Eyes, Take Warning: People possessed by the Pah Wraiths get creepy red eyes. Happens to Jake and later to Dukat.
Red Light District: The upper floor of Quark's bar is dedicated to erotic holosuites, though Quark peddles other illicit wares under the table.
Red Shirt: Isolated incident in "The Search, Part I" when the Defiant comes under attack from the Jem'Hadar. Otherwise, Starfleet comes out unscathed in this series.
That's because the bulk of station security was handled by Kira's militiamen (Red) and Odo's deputees (Gold). All in all, the reds took more punishment during the 7 years, though a couple constables got shot by Klingon boarding parties and the like.
Another incident in "Civil Disorder" - the only on-screen death is a red shirt.
In Trials and Tribble-ations, a Star Trek: The Original SeriesRedshirt is in mortal peril from a mad Klingon—but survives (probably because Kirk, Spock, and McCoy were also in harm's way—Kirk was the target).
In Empok Nor, DS9 is in need of repairs, and so it's decided to pay a visit to DS9's abandoned twin in order to obtain spare parts. Along for the ride are three members of the main cast, and four new faces. The newcomers actually get quite a bit of dialogue, but by the end of the episode they're all dead.
Reincarnation Romance: Sort of. Dax and another Trill consider continuing their relationship from when both were in previous hosts. They eventually decide not to, as this is considered a massive taboo by Trill society.
Religion of Evil: The Cult of the Pah-Wraiths. Mainstream Bajoran religion (correctly) portrays the Pah-Wraiths as Always Chaotic EvilOmnicidal Maniacs. Members of the Cult (who don't call it a "cult", obviously) believe that the Pah-Wraiths have been Mis-blamed and the Prophets are the villains, even before Bajor's Arch-Enemy Dukat showed up and took over claiming to be receiving visions and commandments from them. The problem, of course, is that they really are giving Dukat visions and commandments, possibly up to and including Kill 'em All in order to conceal the fact that Dukat is still a womanising murdering Manipulative Bastard. That it really was their idea, and not Dukat just covering his tracks via mass-murder, is pretty damn sinister, but their followers don't believe them to be evil (one even goes through with the suicide because he believes that, despite Dukat's treachery, they really did order it, and kills himself out of "faith") and in fact believe them to be good. Nevertheless, the Cult of the Pah-Wraiths was so misguided that it was historically considered a joke on Bajor because, to most Bajorans, it was very obviously a Religion of Evil rather than a Path of Inspiration (which its easily deluded followers make it superficially appear to be).
Remember The New Species: In "The Adversary", we're told of a species named the Tzenkethi, who fought at least one war against the Federation in the past 20 years; the TNG era is in its seventh season and this is the first we've heard of them. (And we never do actually see them on-screen).
We're left to assume that the Federation is a pretty big place, and is probably nominally at war with a handful of people at any given time. Assuming that the Tzenkethi aren't a power on anything like the scale of the alpha quadrant empires means that a 'war' probably involved a task for of a few dozen ships. The Federation is all about proportional response after all.
Retro Universe: Looks like San Francisco got absorbed into the Capitol of Panem sometime in the 21st century. ("Past Tense") The slums look fairly contemporary, but then we cut to Dax trying to blend in with the upper crust, complete with a striped petticoat, Emily Bronte hair, and decorative hair feather(!).
Retro Upgrade: Old Klingon ships were protected against the Breen energy-draining weapon, by an obsolete component (it might even have been a reference to the outdated plasma coils in the cloaking system from Star Trek: Generations).
In the episode "Tosk", O'Brien offers his assistance to fix Tosk's ship, but doesn't know how to go about it unless he knows what the broken part actually does. Tosk explains that it collects interstellar particles and converts them into energy for the engines. Miles compares it to a ramscoop used to suck in air. With that comparison in mind, Miles is able fix the ship and improve its performance.
The Reveal: In the 3rd season, when it's revealed that the Changelings are the head of the Dominion.
A few years later Gul Dukat is revealed to be working with the Dominion.
And a few episodes later, when it is revealed that Bashir is in a Dominion prison and has been replaced by a Changeling for most of the season. The real Bashir is wearing the old uniform, giving the viewers a precise indicator of when Bashir was snagged.
Revenge Before Reason: In "Ties of Blood and Water", we see in a flashback that during her time in the resistance, Kira Nerys let her father die alone because she was out hunting down the Cardassians who shot him, even though he asked her to stay with him.
Humorously played up by Quark who says that once Morn starts talking, he never shuts up.
Morn actually laughs- as in audibly- in "The Nagus". So you get precisely one hint in the entire run of the show as to what he'd sound like. It got to the point where the make up artists actually redesigned Morn's prosthetics to allow his lips to move more naturally on the chance he was ever actually given a line.
Used less often than Morn was the thrice-mentioned Lieutenant Vilix'pran and his increasingly bizarre alien biology, from wings to reproducing through budding, requiring a hatching pond and at least eight to eighteen hatchlings per reproduction.
Not to mention Captain Boday, whose only defining trait (other than having an on-again-off-again relationship with Dax) was having a transparent skull, which was mentioned every time he was.
Around season four or five there were several references to "waste extraction" scattered about in various scripts.
The Alamo in season seven. Some people thought it might be an allusion to how the series would end, but no, it was just a plotline thrown in because producer Ira Steven Behr had a soft spot for the Alamo. Combined with their 300 scenario and earlier Battle Of Britain obsession, it made counsellor Ezri a bit worried about Bashir and O'Brien.
Three words: Self-sealing stem bolts. They even made it into the MMORPG.
There's a minor one in the early seasons involving Sisko's nonchalant reaction to being punched in the face. The two most notable examples are Q-Less and Fascination.
In Q-Less, Q, an omnipotent being, taunts Sisko by recreating a nineteenth century boxing ring. He punches Sisko with bare knuckles no less than four times before Sisko reacts at all: he blocks a fifth blow and knocks Q right on his butt. Q looks shocked, but Sisko just shrugs as if to say "That's what happens when you hit me."
Q: "Picard never hit me!!!"
Sisko: "I'm not Picard."
Fascination has a love-sick Bariel who believes that Sisko is a competitor for Dax's affection. While Sisko is trying to explain that he is not interested in Dax, Bariel punches Sisko in the jaw—after which Sisko continues talking with absolutely no change in his body language or tone of voice.
Quark's series of Vulcan Love Slave holosuite programs.
Sacred Scripture: The Rules of Acquisition for the Ferengi. Actually they are a set of business guidelines, but they are said to be divinely inspired.
A more conventional version are the various Bajoran Prophecies that are quoted, and often misinterpreted, throughout the series.
Sadistic Choice: In the episode 'For the Uniform', Eddington gives Sisko the choice of rescuing Cardassians or catching him. And then Sisko, of all people, gives one to Eddington when he demands he gives himself up to save the Maquis (or their worlds, at least).
Salt the Earth: After Starfleet is forced to abandon Deep Space Nine to the Dominion and the Cardassians, Kira Nerys destroys the computer systems. Between this and the budding Bajoran Resistance, the station doesn't become fully operational again until partway into the sixth season (just in time for Starfleet and the Klingons to build up their forces enough to take it back.)
Shows up in the pilot too. The departing Cardassians did their level best to make sure that both Bajor and the station were as inhospitable as they could leave them.
Saved By The Phlebotinum: Averted in "Children of Time". The episode made it seem at the midpoint that both the crew and their descendants could be saved by duplicating themselves, but it turned out there was no Take a Third Option, and that a Sadistic Choice had to be made. Odo ended up making it for them.
Save The World Climax: Starts with the Federation taking over an old starbase from the Cardassians who'd recently withdrawn from a long brutal occupation of the planet Bajor which the starbase orbits. Episodes involve the rebuilding of Bajor and its various growing pangs of independence (and bitterness over its recent past), and some exploration through a wormhole recently discovered near the station. But a great power lies on the other side of that wormhole, which soon puts the whole Alpha Quadrant in jeopardy in the large-scale Dominion War.
Scars Are Forever: Martok's eye & scar. Though in this case it's made clear Martok could get a prosthetic eye, he simply refuses to.
Also Furel, a Bajoran resistance fighter, and his arm. Starfleet later offers to make him good as new, but since he saved others and escaped with just a lost arm, he refuses.
In "Facets", Sisko is (voluntarily) taken over by one of Dax's former hosts, a serial killer (the aforementioned Joran). His delivery is creepy, and according to the Star Trek Wiki, there is a take of that scene that was even creepier.
When Ezri is unsure about joining the crew, she lets slip that even Worf is intimidated by Sisko.
Ezri: You like that, don't you? Sisko: [Completely failing to restrain his amusement] Of course not. Ezri: Oh, come on. I've been a man; I know!
The Maquis story arc pushed Sisko's Berserk Button quite often, ultimately leading to him firing torpedoes that would spread biogenic weapons that were lethal to Humans across the entire planet's atmosphere, forcing the Maquis colonists to evacuate. All because they had already done the same to two Cardassian colonies (rendering them uninhabitable for Cardassians, but safe for the Maquis), and would've done it to more. They pushed him too far that time. He was angry, and he wasn't going to let them get away with what they were doing.
Scoundrel Code: The Ferengi Rules of Acquisition, which range from harsh ("A Ferengi without profit is no Ferengi at all.") to pragmatic ("You can't make a deal if you're dead.") to Pet the Dog ("Good customers are as rare as latinum. Treasure them.")
Scotty Time: Sisko is impatient when it comes to the Defiant's maintenance, as O'Brien can attest.
Seriously Scruffy: This is used as shorthand to show that there's something physically wrong with a changeling. If Odo has gone too long without a regeneration cycle his usually immaculate uniform starts to darken and flake and his slicked-back hair gets crazy. Also seen with the female Founder in the last season, courtesy of Section 31's bioweapon.
Shades of Conflict: The Dominion War has a lot of this. The Federation are the good guys for the most part, but they have secret agents willing to do anything to protect it, and the Klingons are rife with corruption. Meanwhile, the Dominion are responsible for a lot of atrocities back in the Gamma Quadrant, while the Cardassians, while starting out as Space Nazis, fell on hard times and their bad deal with the Dominion eventually pushed a lot of them into the position of The Atoner.
Shameful Source Of Knowledge: In "Dax", the Dax symbiote in Jadzia Dax's body is placed on trial for the crimes of treason and the murder of General Ardelon Tandro. One of the symbiote's previous hosts, Curzon Dax, is the only person who could have committed the crime but didn't have a suitable alibi. General Tandro's widow Enina is incredibly reluctant to involve herself in the trial, but eventually provides Dax with an alibi - she was having an affair with Curzon Dax, and he was in her bed at the time when the crime took place.
Garak uses a device on Odo that prevents his shapeshifting to torture him when Odo's body needs to return to a liquid state.
Later, he is turned into a "solid" human by his people as punishment (for half a season).
The Founder's Disease does this to all Changelings during the war, though most of the ones at home just stay in liquid form anyway.
Shoo Out the Clowns: "The Dogs of War", the series' penultimate episode, concludes the Ferengi arc, sends Rom and Leeta to Ferenginar and Zek and Ishka to Risa. This removes all of the comic relief characters in time for the series finale.
In the penultimate episode, Quark cops some of Picard's speech from Star Trek: First Contact to defend the sacred Ferengi practice of sexual extortion from employees.
Morn is an anagram of Norm, from Cheers. It was entirely intentional.
In the comedic episode "Trials and Tribble-ations," the two agents who show up to investigate Sisko's time traveling shenanigans are named Dulmer and Luscly, anagrams of "Mulder" and "Scully" from The X-Files.
When the occupying forces on DS9 in The Siege find that Odo (the shape-shifter) is missing, their commander concludes the situation is "more than meets the eye".
In Looking for Par'Mach in All the Wrong Places, Quark states his opinion on war, and what it is good for. Absolutely Nothing.
The Breen's refrigeration suits are modeled after Princess Leia's disguise as Ubese bounty hunter Bouschh in the beginning of Return of the Jedi.
Occasionally, Odo's investigations and questioning of people would end in a final "just one more thing..."
The scene in "Chimera" in which Odo and Laas discuss their relationships with humanoid women may be a shout-out to a similar scene in Highlander. Laas warns Odo that Changelings cannot reproduce with humanoids, just as Ramirez warns MacCloud that immortals cannot father children. Laas also warns Odo that as a long-lived Changeling, he will have to watch Kira grow old and die, just as Ramirez warns MacCloud of the same heartache awaiting him with his mortal wife.
Look out there. Millions and millions of stars. Millions upon millions of worlds. And right now, half of them are fanatically dedicated to destroying the other half. Now, do you think, if one of those twinkling little lights suddenly went out, anybody would notice? ... Suppose I offered you ten million bars of gold-pressed latinum to help turn out one of those lights. Would you really tell me to keep my money?
Silent Offer: In "Past Prologue", Garak negotiates the price for a terrorist with two Klingons in this way, using an electronic tablet instead of paper.
Sitting Sexy on a Piano: Lola ( a holographic Major Kira lookalike produced by Vic Fontaine to help Odo learn to flirt with her) uses this pose to flirt with Odo in "His Way."
Slap-Slap-Kiss: There's no actual slapping going on, of course, but the first kiss between Odo and Kira takes place at the culmination of a rather heated argument.
Worf and Jazdia take this trope literally.
Slave Collar: In one alternate universe episode, the captured Garak is restrained this way by Worf.
Sliding Scale of Idealism Versus Cynicism: Started out as optimistic — but still not so cheery, considering the themes of Sisko's bereavement and Bajor's Holocaust-like recent history — as the other series, only to head straight into the Dominion War arc by the third season, and slamming straight into the very end of the Cynical side of the scale in the second to last season with the episode "In The Pale Moonlight".
However, have a look at the final episode. After all the politicking, the plotting and the treachery, what finally brings the Dominion War to an end is Constable Odo doing exactly what all the cynical people had feared the most: sharing the disease cure with the Founders. If that's not pushing way back to the idealistic side, I don't know what is!
Smart People Play Chess: Sisko has a 3-D chess set in his office. He's also been seen playing traditional chess with Dax.
Space Mines: During the Dominion Wars the Defiant mined the entrance to the Bajoran wormhole.
The Klingons established an illegal cloaked minefield in "Sons of Mogh." The mines were dormant and had to be remotely activated in event of war — and would effectively cut DS9 and Bajor off from support from elsewhere in the Alpha Quadrant.
Space Western: Not a direct example, but draws on several Western tropes such as the frontier town near a strategic pass, the bar, the sheriff, etc.
Bashir gave this a shout-out in the first episode, waxing poetic about how he chose Bajor over any other posting or research grant because it was in the "farthest reaches of the galaxy", which would let him practice "frontier medicine" "where heroes are made". Unfortunately, he chooses to wax poetic about this in front of local Bajoran representative Kira Nerys, who is...unamused.
Sparse List of Rules: The Rules of Acquisition. There are canonically 285 of them, though less than 100 are actually mentioned in the show. The first Rule was actually devised by the first Grand Nagus, and named "The 162nd Rule of Acquisition" as a marketing ploy to create demand for the first 161. Rule #1: "Once you have their money, never give it back."
Spinoff Sendoff: The pilot starts with The Enterprise-D docked at Deep Space Nine. Captain Picard appears and Commander Sisko promptly tells him how much he hates him. Sisko has some epiphanies, makes peace with Picard, and Picard gives him his blessing.
Spot the Imposter: This is most of the plot of "The Adversary." However, this is subverted during the climax when O'Brien is faced with a choice between two Odos and decides to get back to fixing the Defiant.
"I've got more important things to do than play Choose the Changeling."
Staff of Authority - The Grand Nagus's staff, which Ferengi are supposed to kiss as a sign of respect.
Star-Crossed Lovers - Jadzia Dax and Lenara Kon. Despite being parted for multiple hosts and being different people, they still love each other so dearly that the only reason they part is because the cost is so high.
The Stateroom Sketch - A confirmed homage in "The Circle", though it's in Kira's quarters rather than a closet and it's pretty much friends barging in intending to wish farewell privately. All done in one take, though the final cut has reaction shots cut in.
State Sec - The Cardassian Obsidian Order, which Odo says records even what Cardassian citizens eat for dinner. The Ferengi Commerce Authority also comes across as this at times.
The Romulan Tal Shiar. They survived the joint operation with the Obsidian Order, continue to operate their own ships, and factor heavily into the Empire's role in the Dominion War. (Though some of those ships are actually seen over on Voyager, in "Message In A Bottle".)
The Federation's Section 31, although it's more of a clandestine Black Ops organization.
Stay in the Kitchen: Humorously inverted by Sisko's father (a cajun restaurant owner) in "Homefront" when he proclaims that Sisko's sister "has no business in the kitchen" because she can't get his recipes right.
STD Immunity: Averted with the Section 31 virus that afflicts the Changeling race. The virus is spread through linking, the closest Changeling analog to sex. To bring about a Changeling genocide, Section 31 infects an unwitting Odo, who unknowingly infects the Great Link (and probably Laas as well). By season 7, the virus has spread like wildfire through the Great Link, threatening the survival of the species.
Stealth Pun: In "A Time To Stand" they have to perform a mission piloting a captured Jem'Hadar ship. One of the first things they notice about the ship is that there are no chairs...
Straw Hypocrite: Vedek Winn in "In the Hands of the Prophets". The show starts out with her criticizing Keiko's secular teaching regarding the wormhole, and the stage is set not only for a debate between science and religion, but also a discussion of the tensions inherent in multiculturalism and diversity. However, it turns out that Winn's protest was simply a ruse to lure Vedek Bareil to the station to assassinate him.
Straw Vulcan: Capt. Solok from "Take Me Out to the Holosuite"
Played with, since it's made pretty clear both from dialogue and Solok's own reactions that despite hiding behind a veneer of Vulcan logic, Solok often lets his emotions get the better of him.
Stock Footage: Every big battle after Sacrifice of Angels blatantly used shots taken from earlier battles (especially a certain shot with the Defiant and two Mirandas), with the final fight in the finale having almost no original footage.
Stomach of Holding: Morn in "Who Mourns for Morn?". It's revealed that he took part in a robbery years before, and he kept the latinum — removed from the gold in which it's normally stored — in his second stomach, which is why all his hair fell out.
We don't know this - Quark supposes that this is the cause, but we don't know how much Quark knows about Morn's species etc.
Stupid Good: Shades of this manifest in the Deep Space 9 crew as the Dominion War rages on. While they never come close to being full on stupid good, they have way too many reservations about taking extreme measures against extreme threats. One example is in Sisko's anger with Garak in In The Pale Moonlight. Garak rightly points out that you do not hire someone like him unless you are willing to have some deaths on your conscience, and Sisko knew that.
Super Prototype: The Defiant was originally a prototype to be used against the Borg, but was moth-balled after that threat died down.
Suspiciously Similar Substitute: Ezri Dax; Terry Farell left at the end of season six due to contract disputes, but the show still called for a Dax character to finish out the show. Thankfully, the "Trill symbiote" backstory gave them an out to have the character "survive", and they got cuteplucky then-twentysomething Nicole de Boer for a replacement. Fans were (and are) divided on how good a continuation of the character it was.
In the continuation novels, Ezri is given a chance to develop more than she was able to on the show. A few years later she is a Captain, in charge of the U.S.S. Aventine, a pretty badass ship, equipped with slipstream drive and everything, and plays an important role alongside Riker and Picard in the complete defeat of the Borg in the Star Trek: Destiny trilogy of books.
In a non-character variation on this trope, the Defiant is destroyed late in Season 7. A mere four episodes later, the identical Sao Paulo is dispatched to the station, and immediately renamed after the destroyed ship.
Suspiciously Specific Sermon: In "Far Beyond the Stars", the character corresponding to Sisko's father gives some very specific advice to Sisko while giving a street sermon.
Sycophantic Servant: Weyoun and every other Vorta are this whenever a Founder walks into the room. In fact they are genetically programmed to be as such and it seems that any cunning bastardry in the Vorta's characterisation gets diverted from nefarious plotting into finding the best way to suck up.
Synthetic Plague: The Section 31 virus, which quickly spreads through the Changeling population.
Taking A Third Option: This trope is directly quoted by Kira in the third season premiere "The Search, Part I" after the senior staff (minus Sisko) has run many simulations and found that the station will be overrun by the Dominion very quickly in the event of a full-scale assault. Dax says that that leaves them with two options— abandon the station and make their stand on Bajor, or collapse the entrance to the wormhole. Kira says, "I want a third option" and almost at that very moment, the third option appears in the form of the new USS Defiant.
Talking to the Dead: Literally due to a Temporal Paradox. The Defiant receives a distress call in the middle of an interstellar storm and alter their course to the planet in order to help. During the trip, they hold a conversation with a starfleet officer who only managed to keep herself alive thanks to the recommendations of rationing what few medical supplies she had. By the time the crew finally reaches her on the surface, they find that she had been dead long before the Defiant got the distress call.
Techno Babble: A Star Trek staple. Q also refers to it by name during his appearance.
Theme Naming: All the runabouts assigned to DS9 are named after Earth rivers. Lampshaded by Kira in "Family Business".
Kira: You know, the rate we go through runabouts, it's a good thing the Earth has so many rivers.
Theme Tune Cameo: In "Sanctuary," where one of Kira's friends plays a version of the theme song in Quark's.
The Name Is Bond, James Bond: Bashir does this at least twice in the Bond homage "Our Man Bashir", using both his real name and his cover name. Less humorously, O'Brien introduces himself this way to the faux Boone in "Tribunal".
In Past Tense, when a time-displaced Sisko has to fill in for a historical figure who ended up dead on his account, he introduces himself this way. "The name is Bell. Gabriel Bell."
The relationship between the Prophets and Sisko evolves over the course of the series, even though the Prophets live outside of linear time.
The "Orb of Time" exists solely for this.
Arguably the entire point of "Visionary": O'Brien travels a few hours into the future several times and sees things that he has to take steps to prevent. It makes him very uncomfortable when he's sitting in Quark's at the same time he saw himself getting shot in the future, and then later he meets his future self and has a long conversation with him.
Future O'Brien: You don't look too good.
O'Brien: It's the radiation.
Future O'Brien: But if you're feeling bad and you're me, shouldn't I feel bad, too?
Both O'Briens: I hate temporal mechanics.
Token Evil Teammate: Garak starts off as Faux Affably Evil and moves into genuine Affably Evil. He regularly reminds others that he is not a nice person, and is quite pleased when people like Nog or Bashir show absolutely no trust for him. As the show goes on, his friendliness becomes less of an act and more sincere, which is why he is glad to see his friends not being so foolish as to trust such an obviously dangerous man as himself. He's also a unique example in that he is entirely selfless due to his absolute loyalty to Cardassia which results in his alliances shifting depending on who he feels has Cardassia's best interests at heart. He works with the Federation because he feels it's the best way to save Cardassia, and he grieves for the loss of Cardassia's music, culture and art when the Cardassia he knew and loved is gone forever. That said, he'd actively helped to instigate the rebellion that led to the Dominion's attempt to destroy Cardassia in revenge and he knew, and completely supported, Damar's desire for a new Cardassia. He knew his actions would destroy the Cardassia he loved (although the extent of the destruction came as a shock to him) and he took them anyway because he realised it was the best option left for Cardassia.
Torture Always Works: Averted, as this is one of the rare occasions in Trek where we see the torturer's point of view. One of several accounts of Garak's exile involved Garak aborting an interrogation that was going nowhere.
In "Improbable Cause"/"The Die Is Cast", Garak flat-out tells Odo to lie after torturing him for hours.
Garak eventually starts begging Odo to make up something he can give Tain so that he can stop. Odo does eventually give in, and then Garak lies to Tain about it. Garak is, at the time, far more emotionally upset about the torture than Odo is.
Tain and other professionals easily believe that someone can withstand torture - that is, they don't think torture always works.
Torture Technician: In "Improbable Cause"/"The Die Is Cast", Tain strongly indicates that Garak often played this role for him in the past prior to Garak's exile and, in the episode itself, Tain expects Garak to play that role again to torture Odo.
Trademark Favorite Food: Most of the main cast are fond of raktajino, particularly Sisko. Miles, on the other hand, prefers Jamaican blend Earth coffee, "double strong, double sweet", while Julian drinks Tarkalean tea, and Worf drinks prune juice. While Worf drinking prune juice is a Continuity Nod, it's amusing that he's one of the few who don't drink raktajino, since it's described several times in the show as "Klingon coffee."
Totally Radical: If the "Past Tense" episodes are right, we'll be saying "check your e-mail!" to mean "get a clue!" in the 2020s.
Tragic Villain: Gul Dukat presents an especially deep version of this trope. Through the ongoing story it is revealed that the most heinous acts Dukat committed in the past against the Bajorans were done not simply because he was ordered to, nor because he was especially malicious. He carried out his most egregious acts knowing that if he refused to do so, he would be replaced by someone who would. Not only that, but someone who would not make an effort to minimize how much horror they inflicted, but may actually enjoy it enough to do more than is necessary. Even before this Dukat is shown several times as a family man who genuinely cares for his family, and at some points seems to regret his career choice as it takes him away from his children who can't understand why their father is not at special events such as birthdays.
Later, Dukat loses his family when it is revealed he has a half-bajoran daughter. After that he sees that same daughter who he lost his family over murdered in front of his eyes after she admits to betraying him and his cause. This results in Dukat undergoing a mental breakdown from which he never truly recovers. As a final addition of insult to injury, during his mental breakdown he tries to explain himself to Captain Sisko, but is unaware that Sisko cannot see the hallucinations that he (Dukat) is himself experiencing. As a result, Sisko only hears Dukat seemingly making light of the dreadful things he has done, while missing out on the exposition that if Dukat had not acted as he did; someone who would have done worse would have replaced him leading to even more suffering. Thus Dukat does not even get to keep the respect of his Worthy Opponent, who thereafter views him as a monster.
He ultimately ends as a subversion, though. Despite his protestations to the contrary, Dukat eventually embraces his villainy when he admits that he always despised the Bajorans, and for rejecting his "sympathy" during his rule on Bajor (read: slave labor quotas are reduced by a generous 50%), he thinks he should have exterminated them all. Thereafter he becomes an Ax-CrazyOmnicidal Maniac.
The Expanded UniverseHand Waves this by saying that you can get a real-time link through subspace only for a limited distance. To have a broad region (like the entire Federation) available in real time, you need a network or relay beacons (one of which appeared in a Star Trek: TNG episode). There are beacons set up to provide such links between Earth and Bajor, but not out into the uninhabited and hard to navigate Badlands.
An egregious example can be found in the series finale: while Kai Winn and Dukat are hanging in the Fire Caves, trying to summon the Pah-Wraiths, the joint Alpha Quadrant forces fly to Cardassia, wage war with the Dominion, conquer Cardassia, fly back to DS9, hold a peace conference with the Dominion, and have a victory party aboard the station. Either this was the fastest war ever, or Winn and Dukat spend days if not weeks inside the Caves.
Keiko O'Brien appears in relatively few episodes, but when she does it is mostly to be cranky and domineering. There are many other episodes in which she antagonizes her husband, Miles, from somewhere off-camera. Her bouts of 'mushiness' are mostly limited to self-important meddling in the affairs of others.
Kira Nerys. Oh Prophets, Kira Nerys. Fiery RedheadedBadass who goes positively kittenish at certain points with her romantic interests - particularly Odo.
Quite rarely for Star Trek, the episode "Past Tense" plays this straight, when Sisko, Bashir and Dax accidentally time-travel to 2024 Earth. There's no fantastic issues involved, it just takes contemporary political issues and technological developments from The Nineties and exaggerates them.
If it had been filmed a decade later, "Tribunal" could have been seen as a parody of reality TV in general and the Cardassian Judge a parody of Judge Judy.
Twist Ending: "In the Pale Moonlight" has one of the best Twist Endings in Star Trek. It starts with Sisko dictating his log to the computer in a state of deep depression, explaining the unethical plan he'd concocted together with Garak to trick the Romulans into declaring war on the Dominion and talking about how "it all went wrong". Near the end of the episode the Romulan senator who he presented his forged evidence to has seen through his plan and left in a fury, intending to expose the "Federation treachery" to the Romulan senate and you think Sisko's misery is because he accidentally caused the Romulans to declare war on the Federation instead. Then we find out that Garak assassinated the Senator and framed the Dominion for it and Sisko's plan has gone perfectly, with the Romulans declaring war on the Dominion... and that is why Sisko is miserable. But he can live with that.
Sisko is also upset by the fact that, when he learned of the assassination and confronted Garak about it, Garak explained to him that he knew than Sisko knew all along that the 'official' plan wasn't going to work and this is the way that it was going to have to happen, and Sisko came to Garak precisely because he knew Garak would do this. The kicker being that Garak was completely correct and Sisko was just hoping he could lie to himself about it later and feel better. No such luck with Garak around.
Utopia Justifies the Means: A utopian federation with a quasi-evil agency working on the periphery... though Section 31 behaves more or less like modern day intelligence agencies do. The bureau is legal according to the Federation Charter, buried in an obscure sub-section (hence their name).
Vengeful Vending Machine: When the crew accidentally triggered a Cardassian riot failsafe in the station's computers, one of its defensive measures was to have the ops replicator produce a turret to attack the crew.
Vigilante Execution: Heavily subverted in "Duet", one of the best early episodes. Aamin Marritza, a Cardassian file clerk masquerading as a war criminal to force Cardassia's sins to light is stabbed to death immediately upon being released. When Kira tells the assailant the truth, he says that Marritza being Cardassian was reason enough to kill him. The last line of the episode is Kira telling the assasin "No, it's not!"
Played with in 'Duet', where the notorious war criminal Gul Dar'heel's breakdown confirms that he isn't Gul Dar'heel, or even a villain.
Virtual Danger Denial: In one episode, the Aliens Of The Week beam four DS9 crew members into a holographic game parlor. At the end, the situation gets quite dangerous and the crew members seem to die - only, to their own surprise, to turn up perfectly okay back in Quark's bar. May be justified, because holographic simulations actually can turn lethal in the Star Trek universe.
Visions of Another Self: Sisko has a vision of being a '50s sci-fi writer, and his associates were versions of people he knew.
The Voiceless: Morn. A fan myth was that he would speak the last words of the series, but didn't happen.
The Expanded Universe has made a Running Gag of Morn actually being exceptionally loquacious (whenever he's not on-screen), with the novel Rising Son even having Jake opine that once Morn starts talking, the trick is in getting him to shut up.
It started even before then, with characters discussing how talkative he is on the show.
Morn can be heard laughing in the episode The Nagus. It's the only time in the series we hear a peep out of him.
Voice of the Legion: When Gul Dukat becomes the Emissary of the Pah-Wraiths so that he can destroy the Alpha Quadrant and gains superpowers in the process, his voice becomes significantly deeper and echoes.
Waif-Fu: Kira is pretty small, but was a feared terrorist/freedom fighter and a badass in battle.
War Is Hell: Existing from the middle of the series and forward but especially in the episode The Siege of AR-558.
The War on Straw: Eddington's "The Reason You Suck" Speech to Sisko in "For the Cause" is undermined by the fact that the Maquis didn't just leave the Federation; they committed terrorist attacks that threatened to undermine an important peace treaty with Cardassia. Even more so with Eddington, who (ostensibly) remained part of the Federation, a Starfleet officer no less, whilst secretly working for the Maquis.
And subverted in "Paradise Lost": A Founder states that they aren't everywhere, and indeed, aren't even in most places at all. But that doesn't matter because they don't have to be - they can be anywhere, pretending to be anyone, and the Federation has no way of knowingwhere they are at any moment. Four agents operating on Earth are able to cause a chain reaction of events leading to martial law being declared on Earth, and a battle being fought between two Starfleet starships that had each been led to believe the other was commanded by a Changeling.
However, they are everywhere important, including Starfleet HQ and the highest levels of the other governments. Their shape-shifting abilities just mean it doesn't take many of them to be everywhere.
We Have Reserves: Combined with Cloning Gambit. The Jem'Hadar are bred artificially in birthing chambers and fully mature in three days, and the Vorta are cloned from currently existing members, replaced when the active one dies or attempts to defect, so the Founders have a pretty blasé attitude towards allied losses that are not Changelings. Later on, they develop this attitude towards the Cardassians, which causes them to rebel and is one of the many causes for the Dominion's downfall.
Odo towards Doctor Mora Pol, the Bajoran scientist who discovered him. Odo admits he's never wanted anything more than his respect and for him to think of him more as something to be studied and experimented on in a laboratory. Odo also reveals he purposefully imitated Mora Pol's hair because he respected him.
Also most (if not all) of Section 31. Also qualifies as Utopia Justifies the Means, since they're willing to commit any crime, no matter how monstrous, to protect the Federation.
Admiral Leyton in "Homefront/Paradise Lost." He pushes for more and more security measures in order to put Earth under martial law so as to combat Changeling infiltration after a bombing. He sabotages the planetary power grid as "Changeling sabotage" and fakes a cloaked Dominion fleet to make his case, going so far as to attack another Starfleet ship when they threaten to expose his conspiracy.
"The Search, Part I and II", the first part ending on a cliffhanger with Sisko, Dax, O'Brien, and Bashir's seeming death or capture, the brand new Defiant seemingly destroyed, and Odo finally meeting his people. The next part reveals the Changelings are the Founders, the head of the Dominion.
"Improbable Cause"/"The Die Is Cast": Garak blew up his own shop, Tain is working with the Romulans to destroy the Founders, Garak is willing to forget that Tain tried to kill him and rejoin the Obsidian Order, Tain orders Garak to torture Odo and he does, Odo admits he wants to rejoin the Founders, the leader of the Tal Shiar is actually a Founder and the entire plot was a means to eliminate both the Obsidian Order and the Tal Shiar in one fell swoop... whew.
The series was completely changed after "The Way of the Warrior", with Worf joining the crew, the Cardassians rebelling and forming for the first time a democratic government, and the decades-long allied Klingons declaring war on previously mentioned Cardassians, antagonising the Federation and breaking the alliance, turning them into active recurring antagonists. Finally, the eponymous Space Station had a slight tactical upgrade. This episode set the theme for the rest of the series.
Let's not even start to talk about "Inferno's Light", where the writers decided to just throw everything in the air and decide to keep the status quo about whatever they could catch. The rest, not so much.
"In The Pale Moonlight" not only brings a major change to the direction of the war, it is quite possibly the strongest violation of Federation Principles ever shown in any episode of Star Trek. The worst part is, is that it's really hard to say that Sisko did the wrong thing, that in the long term, the galaxy wasn't a better place thanks to the actions of this episode. That's why he can live with it.
Sisko: "So... I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again, I would... ...So I will learn to live with it. Because I can live with it. I can live with it..."
Noteworthy that Sisko left out to what extent he was an accessory to murder. Sure, he would qualify just for collaborating with Garak, but there's also the large quantities of highly controlled substances used to make biological weapons he sold to someone who was almost certainly going to use them for exactly that. It could be poor writing, Fridge Brilliance or it could be that, whether or not he felt he did the right thing in the long run, that recognizing that really would be more than he could live with. Of course, Garak himself lampshaded this: Sisko went to Garak precisely because Garak could go further than Sisko's morals (as far as Sisko understood his own morality at the time) would allow Sisko to go. In other words, the minute Sisko decided to use Garak, he was accepting, at least subconsciously, and before the plan had even been concocted that he could and would allow events to unfold as necessary to achieve his aim. His computer log was more akin to a conscious acceptance of the unconscious acceptance Garak had referred to.
Female Changeling: "The Changelings are the Dominion."
In "By Inferno's Light"
Gul Dukat: "I'm not attacking the Dominion fleet. I'm joining it."
"Doctor Bashir, I Presume":
Richard Bashir: At no time in our interview with Doctor Zimmerman will we ever mention or even hint at the fact that you were genetically enhanced as a child.
What a Piece of Junk: The Klingon Armada in The Way of The Warrior got a live demonstration of the station's new (at the time) fortifications. It's still a dilapidated originally Cardassian orbital station barely held together; O'Brien, the man principally responsible for the station having any semblance of functionality, gave the fortifications a 50/50 chance of working properly or blowing up the whole station.
The USS Defiant fits as well. A ship designed only to fight the Borg, its flaw is that it was engineered too well, trying to put Galaxy-class firepower into a ship barely a fifth the size. In her first episode, O'Brien and the officers repeatedly complain about the ship's flaws. While she was still beaten by the Jem'Hadar, she would soon wipe the floor with everything she came across.
What Happened to the Mouse?: The excellent episode "Duet" nevertheless leaves some important questions unanswered. Minister Koval insisted to Sisko that if Marritza was at Gallitep, the Bajoran government wanted him, and would have him. Gul Dukat, meanwhile, told Sisko that if "any Bajoran hate-mongers get their hands on him, I'll hold you personally responsible." Sisko authorized Marritza's release, no doubt pissing off Koval, and then Marritza was indeed murdered by a Bajoran hate-monger. So what are the consequences?
Edward Jellico never appears, and is never even mentioned, despite the fact that he is the Federation's foremost authority on the Cardassians, and even negotiated the armistice. (Although Sisko could handily take that distinction by the end of Season 1.)
What Have We Ear?: In "Rejoined", Dax pulls this on Quark, and then later Bashir does too. Apparently his head is full of latinum.
What the Hell, Hero?: "In The Pale Moonlight", in which Sisko does it to himself. Also, "For The Uniform".
Sisko: Commander, launch torpedoes.
Sisko: Commander, I said launch torpedoes!
The above example should be noted as Sisko irrevocably gassing a former Earth colony with biogenic weapons lethal to humans but not Cardassians. He justifies this as they were a Maquis stronghold and they had already done the same thing with similar weapons lethal to Cardassians but not humans. Note that neither weapon took effect immediately, so the colonists were able to evacuate and basically swap planets.
Odo's involvement with the Female Changeling during the occupation of Deep Space Nine, despite the Dominion's brutal legacy and the Female Changeling's prior antics. Fortunately, he snaps out of it and comes to the aid of his friends.
When She Smiles: Sarina of The Jack Pack. Originally catatonic thanks to her senses forever failing to catch up with her brain, her first action after a procedure correcting it is smiling. Bashir is smitten on the spot.
Where Da White Women At?: Completely averted by Sisko. All of his love interests throughout the series, including his dead wife from the Back Story and the few times he ends up in a relationship with an alien girl, are dark-skinned. And the beautiful Jadzia Dax, who flirts with everyone, never ends up in any sort of romantic relationship with Sisko; due to his friendship with Dax's former host, they consider each other to be Like Brother and Sister.
Why Don't Ya Just Shoot Him?: Subverted by the Female Changeling. When she learns that Damar, Kira, and Garak have been captured, she refuses to grab the Villain Ball and simply orders them executed on the spot.
Worf Barrage: Way of the Warrior is notable for giving the trope's namesake two separate aversions. Defiant is having trouble with a couple of Klingon birds-of-prey. When Worf points out that their tactics are not effective, Sisko gives Worf permission to target at his discretion—Worf blows one of the ships away within seconds. Later, on the station, Worf unleashes the most impressive barrage of weapons fire seen in Star Trek to that point...it devastates the attacking fleet.
Also used to great effect in the very next episode when a similar Jem'Hadar ship is blown to tiny bits by a single salvo from the USS Ben Sisko's Pimp Hand.
Averted with the man himself. Compared to his tenure on the Enterprise-D, Worf developed a consistent ability to win fights, particularly when he was forced to fight the Jem'Hadar in to-the-death combat every day. In the end, the eldest Jem'Hadar had kicked his ass, but Worf still refused to give up, forcing the Jem'Hadar to yield instead of simply killing him.
Worthless Yellow Rocks: After the writers realized gold could be replicated, they realized its value would be nothing to a Ferengi. Thus latinum was created, and any mention of gold was retconned into being pressed with latinum.
The gold casings themselves are little more than money clips, as poor Quark learned when he discovered his "inheritance" from Morn.
Quark: Someone's extracted all the latinum! There's nothing here but worthless gold! Odo: And it's all yours! (chuckles) Quark:NoooooOOOOOOOOOOOOOOO!!
Dukat views Sisko in this way, though the feeling isn't mutual.
Quark and Odo. Quark is generally open about it (explicitly using the trope title when they say their final farewell), telling Odo that over the years he's forced him to step up his game and become a better criminal; Odo probably shares the sentiment, but refuses to admit it even in the finale.
There's a straighter play with Sisko in the three-parter about a Bajoran coup. General Krim compliments Sisko on a speech he gave despite having disagreed with everything in it, and later on seems pleased that Sisko didn't abandon the station, but hid there with his crew to take it back from the Circle. Even though he opposes Sisko at every turn, he clearly likes and respects the man.
When the Klingons attack DS9, there is a scene during the battle where Martok and Gowron are speaking in Klingon. Though a translation is not provided on-screen, it has been translated:
Martok: They fight like Klingons!
Gowron: Then they can die like Klingons. Destroy their shields. Prepare boarding parties!
Martok: As you recommend. All ships, concentrate fire on their shield generators!
Wouldn't Hit a Girl: Many times with Jadzia Dax, which is something of a subversion of the trope seeing as how her current form is female but Dax has been a male several times before.
In "Dax", when Bashir is trying to help fight off Jadzia's hooded kidnappers, the hood of the person Bashir had been fighting slips down, to reveal that he's been fighting a woman. Bashir hesitates just long enough for her to beat the crap out of him and knock him unconscious.
Later in that episode, Jadzia deliberately stonewalls Benjamin when he tries to get some answers out of her regarding the charges of murder and treason. Furious, Benjamin slams his fist into his hand and exclaims, "Dammit, if you were still a man!"
In "The Way of the Warrior", Jadzia challenges Worf to a sparring session with Klingon bat'leths, which would be their first of many. During the fight, she goads him:
Jadzia Dax: I hope you're not holding back because I'm a woman. If it makes things any easier, think of me as a man. Been one several times!
On the other hand, Gul Dukat certainly would hit a girl, as he shows by decking Sakonna in "The Maquis, Part I" when she's part of a group trying to kidnap him.
Xanatos Gambit: A behind-the-scenes example. The producers and writers decided to have the Dominion be represented by three species: the Founders, the Vorta, and the Jem'Hadar. Worried about the audience not accepting them, it was decided to introduce all three at once within the same three-parter, thus guaranteeing that viewers would accept at least one of them. Fortunately, the audience responded positively to all three species and all three would be shown extensively for the rest of the series.
Although the Vorta were tweaked a bit - their silly energy weapon that was emitted from their heart was gotten rid of after its first appearance, wisely.
You Don't Want to Catch This: The Blight, an engineered plague the Dominion inflicted on the Teplans. Every Teplan is born with the lesions and at some point during one's life they will "quicken" into the terminal stage. The best option then is euthanasia. Try and cure it with modern medical technology and it will make death even more agonizing.
You Don't Want to Know: Played straight in Sacrifice of Angels, when Bashir and O'Brien take turns reciting a verse from Tennyson's "Charge of The Light Brigade".
You Just Told Me: Bashir is up for a major medical award. He insists that there is no chance of victory for him, and so he does not wish to discuss it.
Odo: In that case, why are you working on your acceptance speech?
Bashir: (Hides pad) How did you know?
Odo: (smugly) Just a guess.
You Keep Telling Yourself That: A strange case where, after being a party to smuggling, black market dealings, forgery, and murder, at the end of the log where he's recording this, he keeps saying "I can live with that", as though he's telling himself this.
You're Not My Father: In "Cardassians", a Cardassian war orphan who was adopted by Bajorans and raised to hate Cardassians says this to his biological Cardassian father when speaking to him for the first time.
Your Mind Makes It Real: Garak's bloody nose while in Odo's "dream" manifests itself in the real world as he lies unconscious in the infirmary.
Your Mom: In "The Way of the Warrior" Klingons attempt to insult Odo in Klingon, and Garak responds with "Actually, I'm not sure Constable Odo has a mother."
Also, from "The Siege":
Bashir: Quark, leave it!
Quark: I can't leave it, it's all that I have. My personal mementos, my family album...
Bashir: It's full of gold-pressed latinum, and you know it.
Quark: ...Who told you?
Bashir: Your mother did, the day you were born.
Quark: NEVER-MAKE-FUN-OF-A-FERENGI'S-MOTHER. Rule of Acquisition Number 31!
Of course, there's a second part to that rule: "Insult something he cares about instead."
Trill marriages are "until death do us part". Too bad if you die and come back from the dead: The love of your life is now taboo forever. Even worse, the cycle of life in the elite circles of Trill society is based on a kind of reincarnation. Jadzia falls prey to this in one episode, falling head over heals in love with her ex-wife. Nobody even notices that they are of the same gender, the ethical/cultural problem is all about them having been husband and wife in a previous life.
In "Family Business" Rom walks into his mother's room to find her wearing clothes, and averts his eyes until she relents and undresses.
The Bajoran freedom fighters in the backstory of Deep Space Nine used whatever means necessary to free their home planet from Cardassian rule, though it seems that suicide bombings were not standard procedure. The Cardassians (with some justification) prefer to call the Bajoran freedom fighters terrorists. Gul Dukat even called Major Kira a terrorist to her face... and she didn't deny it. Indeed, she's kinda proud of it. There's a point where Kira finds the Cardassian file on herself, and she's actually upset that they only looked at her personally as a minor nuisance. In "The Darkness And The Light", Kira outright screams her defense of terrorism (at least when it comes to Occupiers Out of Our Country) to a Cardassian who's taking revenge on members of her former resistance/terrorist cell, who maimed him in a bombing:
"None of you belonged on Bajor. It wasn't your world. For fifty years you raped our planet, and you killed our people. You lived on our land and you took the food out of our mouths, and I don't care whether you held a phaser in your hand or you ironed shirts for a living. You were all guilty andyou were all legitimate targets!" (This last was because he made a point of noting he'd only been a civilian worker, rather than a soldier, during the occupation on Bajor).
The same can be said of the Maquis and their tactics against the Cardassians.
The Cardassians themselves used terror tactics against the Dominion when the latter occupied the Cardassian homeworld. Kira even went to the Cardassians to teach them how to properly set up a terrorist cell. They actually called them that: terrorist cells. Yes, DS9 is a pre-9/11 show; why do you ask?
You Shall Not Pass: Concerning the deaths of both Eddington and Kor. Also happens in "The Homecoming", where a few of the Bajoran prisoners stay behind and hold off the Cardassians so that Li Nalis can escape from prison.
You Talk Too Much: In "Vortex," which becomes Harsher in Hindsight later in that episode when it starts becoming clear that Croden isn't as much of a liar as Odo thinks and he is likely a political refugee for what amounts to doing just that.
Odo: I think I finally figured out what crime you were found guilty of on your world.
Croden: What's that?
Odo: You talk too much.
In "Indiscretion", Kira says this to Dukat:
Kira: Commander Sisko was right; you are in love with the sound of your own voice.
YouTube Poop: The scene from "In the Pale Moonlight" where Vreenak yells "It's a FAAAAAKE!" is growing in popularity.
Zeerust: Notable as it's easily the least affected out of any of the Trek shows so far; part of this is due to largely being set on an alien space station with somewhat odd architecture, making it easier to gloss over any breaches of plausibility. The Defiant's military bridge has also withstood the test of time very well so far.
As of the 2010s, there is another techology catch-up—compare Google Glass to the Vorta headset.
Zerg Rush: The Jem'Hadar attack with massive numbers of ships, due to the "disposable" nature of the species.
Zero-G Spot: In "Melora," the titular character is an alien from a planet with very low gravity. She and Dr. Bashir get it on in her quarters while the gravity is turned off.
Zip Me Up: Odo zips up Kira's dress in "Badda-Bing, Badda-Bang."