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He Knows Too Much
aka: You Know Too Much

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"Money buys a man's silence for a time. A [crossbow] bolt in the heart buys it forever."
Petyr "Littlefinger" Baelish, Game of Thrones

An organization or bad guy is involved in something dirty, or just did something nasty. Could be The Government, could be The Mafia or The Syndicate, could be General Ripper, a Corrupt Corporate Executive, or an Ancient Conspiracy. No matter who the bad guy was, somebody saw it all, heard it all, or somehow caught wind of what's going down (or what went down), and the bad guy in question has found out about the witness.

Since the witness now knows too much, the bad guy's entire scheme may come crashing down, so they aim to "silence" the witness in some manner, through bribery, blackmail, intimidation, or even "sealing his lips permanently".

A common variant is that the person who purportedly knows too much is The Everyman who doesn't actually know anything at all (or at least, doesn't understand what knowledge they have) — but the overly paranoid conspirators believe that they do, thus leading to their campaign of persecution and intimidation. There's a good chance the hero will eventually get sick of being relentlessly hounded/threatened/shot at by the conspirators and start fighting back. In the process, they usually learn the "real" secret anyway by constantly coming into contact with said conspirators at every turn and eventually will find a way to bring the plan to ruin. The ironic conclusion, of course, is that if the Big Bad had just relaxed and left the person alone, they'd have succeeded.

If it isn't the hero getting persecuted, it will likely be someone the hero cares about, which will usually prompt either a bodyguard scenario as the hero tries to protect them against the bad guys, or a Roaring Rampage of Revenge if the loved one is killed. Either way, it's an excellent MacGuffin.

The most common motive for bad guys to go after innocent people, and also part of the reason that the U.S. Marshals Service has the Witness Protection Program (in addition to protecting witnesses from retribution after they testify).

Another, less sympathetic variation occurs when a character learns a guilty secret possessed by another character and decides it would be a profitable enterprise to blackmail the second character in exchange for their silence. This one usually overlaps with Asshole Victim, since the second character understandably won't like the idea of being on the hook to a sleazy blackmailer for the rest of their life, and is likely to decide that getting rid of the blackmailer will cost them less in the long run than paying up. If the blackmail victim's guilty secret is that they are a murderer, this may also add elements of Too Dumb to Live to the blackmailer — after all, someone who's already killed at least one person is unlikely to have many qualms about bumping off someone else, particularly if that someone else is trying to exploit them for money.

See Revealing Cover-Up, Have You Told Anyone Else?, and His Name Is.... If this trope involves someone finding out about the supernatural, see Killed to Uphold the Masquerade. If it involves a member of the organization being targeted for finding out too much about their employer, see Hunting the Rogue. If the dangerous knowledge is a natural result of their employment, the boss might be planning to Shoot the Builder. See also Leave No Witnesses for those situations where a roomful of people all Learn Too Much at once. Where the knowledge itself is harmful, see These Are Things Man Was Not Meant to Know. Compare also with You Have Outlived Your Usefulness. Compare and contrast Diagnosis: Knowing Too Much, where the one with the knowledge has their credibility assassinated rather than themselves.


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    Anime and Manga 
  • Attack on Titan:
    • Pastor Nick is a high-ranking member of the Church of the Wall and knows many important secrets. As soon as he becomes willing to reveal what he knows to Historia Reiss, members of the 1st Brigade torture and murder him.
    • Alma, the mother of Histoira Reiss and mistress of a certain nobleman, was murdered to clean up any loose ends.
    • When Erwin Smith was young, his father had a theory that the Goverment must have brainwashed to populace within the Walls to hide the truth about the Titans and the world beyond the Walls. The Military Police eventually found out about this and tortured his father to death.
    • Marco Bott overheard Reiner and Bertolt discussing their plans, and was so shocked that he confronted them directly about it rather than reporting them. In a panic, Reiner chased him down and got Annie to help by stealing Marco's gear. The three left him to be eaten by a Titan, though they weren't very happy with what they'd done.
  • What spells the undoing of "Groovy Guy" Russel from Black Lagoon. When he catches on that resident Nun Too Holy Eda happens to be a CIA agent. And in a spectacular display of foolishness, tells her this revelation to her face. He doesn't last long after that.
  • In the original manga of the Hentai series Bondage Fairies, main heroine Pfil is invited into the home of a trio of sisters while on a missing-stag-beetle case. While there, she accidentally stumbles upon a detached stag beetle leg. The sisters realize that they've been found out, and they knock Pfil out and take her captive, starting the plot.
  • Case Closed features many, MANY cases:
    • The series starts with this trope: Amateur Sleuth Shinichi Kudo comes across a mysterious black man extorting from another man, but he fails to see the black man's partner, who sneaks on him and knocks him out cold with a lead pipe. The two try to force-feed him a poison pill plus a serum... but the pill only shrinks him into a body of a child and assumes the alias of Conan Edogawa.
    • In the Ski Lodge case, this was the reason for Minako Mochizuki's murder: she found out that two of her three favorite teachers were involved in a fraud, so she tried to confront them... so the two strangled her to death and then made it look like she committed suicide. And the third teacher? She killed them as part of her plot to get revenge for Minako's murder.
    • In the Luxury Liner case, Tatsuo got beaten to death by his wife Aki's cousin Ichiro because Tatsuo saw him trying to drop the killing weapon (a knife which he used to kill his grandfather) in the sea.
    • The Non-Serial Movie Phantom of Baker Street reveals the immediate reason for Hiroki's death is because he found out Schneider was the direct descendant of Jack the Ripper.
    • In another Non-Serial Movie, a boy named Touma Tachihara witnessed a murder committed by one of his mother's friends, who then kidnapped him and tried to kill him. However, Touma then fell off a cliff and fell in a coma, only waking up eight years later. The killer targets him again, fearing that if he ever recovered his memories, he'd denounce him.
    • Almost happens to Ran Mouri twice, once in the anime/manga and later in a Non-Serial Movie. In the first, she steps inside several rooms where guys are undressing, but one of them has a secret... and he's the killer of the case. In the second, she clearly sees the face of a murderer who immediately tries to shoot her dead, and even when she has a huge Trauma-Induced Amnesia he still attempts to murder her.
    • In the "Timeless Sakura Love" case, Sumiko Kobayashi finds herself in this position after she stumbles in a murder scene and catches a glimpse of the culprit. Good thing that Shiratori, Sato, and the Detective Kids manage to help her and keep her safe.
    • It's implied that Akemi Miyano might have been at the receiving end of this trope. The Black Organization couldn't outright murder the woman because they needed her to keep her younger sister Shiho/Sherry's loyalty in check, but once it was clear that Akemi was in love with a man who had been The Mole in the group, they decided to create a situation where they could eliminate her by having her do a bank heist she was supposed to fail... and which ended up with two agents of the group, coincidentally the same two who shrunk Shinichi, shooting her dead.
  • Aleister Crowley of A Certain Magical Index has spent a tremendous amount of effort making the world think he was dead. He finally reveals himself for the first time in many years to kill Fiamma of the Right after the latter's life is saved by Touma because it risks jeopardizing his long-term plan. Fiamma witnessed the mysterious "invisible thing" in Touma's right arm.
  • Code Geass:
    • In the first episodes of both the first season and R2, Lelouch is about to be shot for having seen C.C., although the second time it was intentional.
    • Rolo Haliburton seems to kill people who know too much on reflex. In an early episode of R2, he murders a Britannian soldier who walks in on a conversation he's having with Villetta for hearing things he shouldn't. And all the guy heard was the word "Geass", which he couldn't possibly have even understood.
    • In R2 Turn 14 (Episode 39 of the series as a whole), Rolo claims to have killed Shirley Fenette for remembering the truth about Lelouch as Zero. This isn't completely true; Shirley wanted to help reunite Lelouch with his real sibling, Nunnally, eliciting Rolo's jealousy. But it's not a total lie either; she knew that Nunnally was Lelouch's sister when she wasn't supposed to. Regardless, this is what provokes Lelouch to destroy the Geass Order, and attempt to kill Rolo as well while he's at it.
    • In Suzaku of the Counterattack, this is why Schneizel had Marianne killed.
  • The driving force as to why The Syndicate keeps trying to kill Spike in Cowboy Bebop. He tried leaving after he met Julia, but his fellow teamsters felt that he would be too much of a risk if he ever got it in his head to squeal on them.
  • In Cyberpunk: Edgerunners, Lucy kills Tanaka Sr. and deletes the data in his head once she discovers his plans to use David as a prime test subject for the Cyberskeleton project. Though he's briefly resuscitated by Maine, he never regains consciousness and dies permanently a little later. Because he over-consolidated the information on the project, Arasaka hires netrunners to reconstruct the lost data. This results in Lucy hunting them down too.
  • In Detective School Q, some people are attacked and either killed/nearly killed because of this trope:
    • Maya Asabuki from the Boarding School case had a videotape that could potentially ruin the plans of the killer, and when the culprit found out, they attacked her to take the tape and silence her. She died in the manga, but (barely) survived in the anime.
    • In a case involving the murder of aspirant actresses during auditions, Sakurako Yukihira was caught searching for evidence by Meiousei agents and put in a cruel Death Trap. Kyuu barely managed to find her before she died.
  • In Four Knights of the Apocalypse, King Arthur has ordered his troops to kill any of The Chosen Many they find- which, because they don't know much about those many, boils down to "kill anyone who's young and unusually powerful". For this reason, Lancelot kills any Camelot knights who penetrate his disguise, to prevent them from reporting back to their king. (Which, conveniently, they always state their intention to do.) Unfortunately, Guinevere's precognition does not rely on meeting him in person.
  • Fullmetal Alchemist:
    • Hughes learns about the Ancient Conspiracy, or at least a little more than the others know. We all know what happened to him...
    • It's not until quite a bit later in the story that the audience is shown exactly what he had uncovered. At first it seemed that he'd discovered little more than that there was an Ancient Conspiracy, and his knowledge shouldn't really have been a threat to them yet. But in fact, he'd also realized that all of Amestris was a giant transmutation circle, a fact that was the linchpin of the entire conspiracy. No wonder the guy got offed.
    • In Brotherhood, Isaac McDougall found out exactly the same thing Hughes did. He also gets offed for his efforts by Wrath/Bradley himself.
    • The two brothers that Ed fights at Laboratory 5 are killed before they can tell him what they know about the Philosopher's Stone.
  • In Future GPX Cyber Formula, Osamu Sugo leaves the Missing Link F-1 team after knowing of his boss Smith's plans to use Asurada, the computer system created by Hayato's father, as a weapon of mass destruction. He soon disguises himself as Knight Shoemach, in order to keep an eye on Hayato, as well as Smith and his men. During his racing duel with his rival Bootsvorz, Smith attacks Osamu from behind with his helicopter's missile for exposing said secret. Osamu survives the incident but ends up injuring his eye.
  • In Ghost in the Shell: Stand Alone Complex, the Major warns a helpful independent hacker who gave her evidence regarding the Laughing Man that he's getting too close to figuring out the truth, which could put his life at risk from whoever is responsible. He thanks her and agrees to back off for his own safety.
  • Gunslinger Girl:
    • When Hillshire learns the girl that he rescued from snuff film merchants and brought to Italy for treatment has been turned into a brainwashed cyborg killer, Jean Croce gives him two options: become Triela's handler, where at least he can watch over her, or be murdered. Either way, he wasn't leaving the Agency a free man.
    • Jean recruits Captain Raballo, whom he served under in the Carabinieri, as The Handler for Claes. However Raballo starts feeling guilty about what's happening to the girls and contacts a newspaper to blow the whistle on the Agency. Next thing we know, Jean is informing Claes that her handler was tragically killed in a traffic accident.
  • In Chapter 23 of Happy Sugar Life, Shouko is murdered by Satou after she had taken a picture of Shio living in an apartment room she "owned."
  • In the TV series of Hellsing, Integra orders Alucard to kill Kim because of the reporter's insistence on letting the world know that vampires exist (as well as Kim's willingness to feed people to vampires in order to get proof of said existence).
  • A variation in Jin-Roh: The Wolf Brigade. Terrorist-turned informant Kei Amemiya was part of Public Security's plot to frame a member of the Kerberos, to discredit the unit so it can be disbanded. She's therefore a potential witness against Public Security, but it's the Kerberos who kill her, to prevent Public Security from tracking Kei down and killing her themselves. As long as she's missing, Public Security can't be sure Kei isn't under protective custody somewhere, ready to give evidence if needed.
  • JoJo's Bizarre Adventure:
    • In Part 3 (Stardust Crusaders), Enya is killed by Dio and Steely Dan (Dio supplied the weapon) so she can't reveal how The World works. The kicker: While dying, Enya made clear that she would never have thought to betray Dio, though Joseph might have been able to read her mind with Hermit Purple. Steely Dan just laughs at her.
    • In Part 4 (Diamond is Unbreakable), Shigechi buys a limited-edition sandwich, but picks up the wrong bag after setting it next to someone else's. The bag he took belonged to Kira, who had left his latest victim's hand in it. When Shigechi opens the bag and sees what's in it, Kira murders him to hide his crimes.
    • Part of Diavolo's plan in Part 5 (Golden Winds) is to murder anyone and everyone who knows anything about him, or has even seen his face. This extends to his own daughter, the Action Girl Trish. Despite the fact that Trish doesn't know anything about her father, having never met him. He's just paranoid that she might somehow know something about him. Fortunately, Buccellati is able to rescue her before he can do the deed.
    • In Part 6 (Stone Ocean), Whitesnake kills Jongalli as insurance against Jotaro and Jolyne learning who's really behind the latter's imprisonment — Enrico Pucci, the prison chaplain.
  • Kaguya-sama: Love Is War provides a non-fatal example. After revealing that she knows about Kaguya and Shirogane's Secret Relationship, Kaguya nearly assaults Onodera with a taser to give her Laser-Guided Amnesia (only for her to prove that she can function as a Secret-Keeper while remaining completely oblivious to Kaguya's attempted attack).
  • Played with in an episode of Lupin III: The Italian Adventure when Nyx's daughter accidentally finds some evidence that would expose Rebecca as a thief. Rebecca seemingly kidnaps the girl, and when Nyx confronts her, she says that she had to do it to "keep her mouth shut". Nyx takes this as an indication that Rebecca has murdered the young girl to silence her, and understandably freaks out. It turns out that Rebecca actually just sent the girl off on an all-expenses-paid shopping trip in order to bribe her into keeping quiet.
  • Lyrical Nanoha:
  • Maria no Danzai: Because she miscalculated how petty and impatient Shikimi was, Maria is forced to improvise and seduce Iijima when he is sent to beat her up for taunting Shikimi. Maria quickly understands that, once she kills Shikimi and her death is investigated, the police could easily draw a connection between Maria and Shikimi if Iijima were to give them her name and face, and decides to kill him to prevent that. Ultimately she can't bring herself to do it after seeing an illusion of Kiritaka remind her that Iijima is not guilty for his death, and Maria agrees that killing him would be excessive; instead, she decides to silence him by other means, but finds that Iijima has disappeared after Shikimi's death. Maria has to race to find him before the police or Okaya's gang can find him first.
  • Mobile Suit Gundam 00:
    • Sent in a message to Professor Eifman just after he figured out the true agenda of Celestial Being's founder, and just before the Thrones attack the base, killing him in the process. Either sent by Ribbons Almack or by Veda itself.
      Eifman's computer screen: "You have witnessed too much."
    • Played with in the case of Kinue Crossroad. She is killed for knowing too much, but the guy who killed her is a violent sociopath, and deliberately gave her the information before killing her for knowing too much, apparently just because doing so amused him.
  • Mobile Suit Gundam Wing:
    • All five Gundam Pilots were ordered to kill anybody who sees the Gundams, or who discovers their identities. Heero takes it to an extreme, by repeatedly threatening to kill Relena for finding him washed up on a beach in his spacesuit. Duo was a bit more forgiving, by simply using a road flare to obscure Relena's view of Wing Zero and Deathscythe and then warning her that it was in her best interests to look away.
    • Near the end of the series, Hilde wound up becoming a target of the White Fang, when she infiltrated the Libra base and hacked their systems to gather data on Vayette and Mercuriousnote . Quantz mobilized them and sent them to silence her before she could get the information back to the Gundam pilots — with the attempt being narrowly subverted, thanks to Duo's intervention. While Hilde is seriously injured, she lives through and successfully gives the info away.
  • Monster: If someone possesses any evidence that Johan Liebert exists, that's enough to have Johan arrange for them to die. The exceptions to this are his sister (whom he considers his "other self"), General Wolf, and Dr. Tenma (the latter two saved his life). Though, he's got his own plans for them. And they are just as evil.
  • Moriarty the Patriot: The British government was after Irene Adler due to the stealing of a top-secret document that reveals a very big conspiracy where Britain pulled the strings of the French Revolution. Since the British government would definitely kill Irene to prevent the scandal, Moriarty fakes Irene's death and Irene joins the MI6 as James Bond.
  • Averted in My-HiME. Akira is duty-bound to kill Takumi if he finds out she's a girl, but not only is unable to go through with it but even saves his life by giving him his medicine.
  • The Mysterious Cities of Gold: After Ambrosius gets information regarding the fourth City of Gold, he gets his informer executed, even though they were once friends.
  • Naruto:
    • Baki kills Hayate after he sees him meeting with Kabuto, learning that the Sand and Sound Villages are conspiring to destroy the Leaf Village.
    • This happened to Kabuto himself, too. He and his mother figure Nonou were spies for Root, but Danzo decided they had become a liability and set them up to kill one another. This was the catalyst for Kabuto's Face–Heel Turn.
  • One Piece:
    • The scholars of Ohara got too deep in researching the Void Century (which is hinted at being a huge threat toward the World Government), and consequently the island, along with its inhabitants, was bombarded into oblivion by the World Government. It's also the real reason why Nico Robin has a bounty; she's the Sole Survivor of Ohara, her mother Olvia was one of the Scholars and she inherited her knowledge. This is also true for anyone who tries to research the Void Century; Pedro's backstory had him leading a crew of explorers in search of the ancient Poneglyphs, but he was surprised to learn that they were labelled as outlaws by the World Goverment for that alone.
    • Also applies to the people of Flevance. When doctors within the city-state — including Trafalgar Law's parents — discovered that it wasn't an infectious pathogen but long-term exposure to the infamous and highly valuable Amber Lead that was poisoning everyone in the country, the World Government and neighboring nations committed mass genocide under the guise of containing a deadly epidemic, killing every citizen except Trafalgar Law, who managed to escape by disguising himself as a corpse in a pile of bodies. Even sixteen years later, the world still widely believes that Amber Lead Syndrome is highly contagious and anyone with it needs to be killed on sight.
    • Played for comedy in Luffy/Ace's flashback. Luffy discovers where Ace and Sabo keep their treasure, and they state that they're going to kill him to keep him from telling, only to realize that neither of them has killed anyone before.
    • During Luffy's fight with Katakuri, Luffy at one point accidentally exposes Katakuri's huge, scarred, fanged mouth to three Tottoland chefs. Katakuri immediately killed them to prevent the secret from getting out, although later on after recognizing Luffy as a Worthy Opponent, willingly let his mouth be seen by others and resigned himself to the inevitable ridicule of his appearance.
    • After Zoro damages his mask, King begins seriously trying to kill him. Once he destroys enough of it that King's own subordinates can see his face, they realize that the rumors about King being a Lunarian are true. They then make the mistake of commenting on how the World Government will offer a lot of money to anyone who can tell them where to find more Lunarians, after which King mercilessly incinerates his own men (or perhaps he was already going to kill them just to be sure).
    • Cobra's assassination took place because Imu revealed themself to him during his audience with the Five Elders; Sabo simply proved a convenient scapegoat to pin the blame on. Wapol, who saw the whole thing through a peeping hole, flees for dear life immediately after, well aware that the same fate awaits him if he's captured.
    • When Saint Jaygarcia Saturn prepares to join the fray in Egghead, all lower-ranking Marines are ordered to clear the area at once and to avert their gaze, while also being warned that disobeying that order will not be forgiven. When a hapless Marine foolishly looks on as Saturn unveils his Awakened Mythical Zoan form, the elder promptly kills him by blowing up his head.
  • Phantom Quest Corp.: In Incident File 04, Detective Karino suspects the Hadja of running a scam operation and gets caught snooping around their compound. Their leader, Mukyo, has him subjected to tickle torture while interrogating him about how much he knows. Then attempts to silence him permanently by dangling him over a pit and summoning the apparitions he'd allegedly exorcised. Thankfully, Ayaka and the others arrived at that time to save Karino's bacon.
  • Pokémon: The Series has this after Prof. Magnolia tells Goh and Sonia not to trust Rose:
    Oleana: Weeds should be plucked as soon as possible.
  • Pokémon Adventures has Ghetsis invoke this on Black after he defeated Team Plasma's King N, not wanting anyone to get wind of the king's defeat as it would harm Team Plasma's public image. He opted to kill the only witness other than himself with a nice smile and polite demeanor.
  • In Promare, Kray Foresight murdered Professor Deus after they completed the technology to assist the world against burnish.
  • In Psycho-Pass, Kagari is killed when they find out the true form of the Sibyl system.
  • In Re:CREATORS, Altair kills Mamika because she discovered the truth about her plans to destroy the world. And also because she mentioned the name of her creator, which was the last straw for Altair.
  • Happens thrice in the first part of Sorcerer Stabber Orphen:
    • Lai steps on who everyone believes to be Childman but is actually Azalie in Childman's body. She turns him into a Human Popsicle, and he remains as such until the end of the first series.
    • Shastanasi, one of the Elders of the Towers of Fangs, also realizes that Azalie has taken over Childman's body and tries to blackmail her. Childman!Azalie fights back, and soon Shastanasi is seen as an Empty Shell.
    • Some time later, Hartia finds the frozen Lai and tries to confront "Childman"... but then he sees Childman!Azalie's shadow in Azalie's form. She almost kills him on the spot and does severely wound him, but he manages to escape to Orphen and Co.'s side and tells them the truth.
  • In Soul Eater Buttaki Joe is butchered by Justin Law when the former levels up his soul sensing abilities and discovers the hide-out of the Kishin.
  • In Talentless Nana, this happens to Ryuuji Ishii by Rentarou Tsurumigawa's hand after the former stumbles on the latters "art" of mutilating wild animals and he's subsequently killed to keep him quiet.
  • In Episode 15 of Tenchi Universe, a Juraian agent orders the Galaxy Police to capture Mihoshi and Kiyone after Mihoshi was listening to a conversation between the agent and the Galaxy Police chief, revealing that the GP had conspired with Jurai in order to capture Ayeka.
  • In Tomodachi Game, the main characters are kidnapped and forced into a Sadistic Game Show before being released under the condition that they never tell anyone. When they do break this rule, bad things happen to the people they told. Tenji's motivation for forcing everyone into the game was that he told his prosecutor father what happened seeking help, only for him to mysteriously end up dead and prompt Tenji to seek revenge. Later on, the same thing happens to Shibe's father when he goes to him asking for help with the debt forced on him, with him getting framed for it.
  • In the Vampire Princess Miyu TV series, this partially is what prompts Dark Magical Girl Miyu to get the otaku Secret-Keeper to fall to his death. The fact that he showed absolutely no understanding about Miyu's nature and what it means to be the Guardian really didn't help his case.
  • Variable Geo: Chiho thought Damian hadn't noticed her while she was eavesdropping on him at the Jahana Research Facility. She overhears one of the lab techs say they'd get better results from Satomi's field tests with live data, rather than simulations. Damian doesn't even bother looking over his shoulder, he simply smirks and tells him to start with the girl spying on them, from the doorway.
  • Allen Schezar's father Leon from The Vision of Escaflowne is believed to have abandoned his family, but this is what actually happened to him. Several years ago, the Zaibach Empire targeted him because he had gathered lots of information on the Draconians and was about to blow their cover. When they managed to find Leon, they took his notes and killed him. His son was so badly damaged by all of this but didn't learn the truth for several years, when he confronted Leon's spirit and tried to call him out on what he believes to have been Parental Abandonment. After learning that Leon never abandoned the family, they eventually make peace.

    Comic Strips 
  • Parodied in one-shot comic strip "Oppgulp" by Frode Øverli in one where a bespectacled nerd carrying a pile of books is about to get pushed down a staircase by a man thinking "He knows too much".

    Comic Books 
  • In Astro City, a petty criminal accidentally discovers Jack-in-the-Box's secret identity. He considers selling the information to the hero's enemies, but then realizes the problem with that plan: the hero's enemies are ruthless villains who would just force the information out of him and then kill him so he couldn't reveal it to anyone else.
  • The Avengers: During Operation: Galactic Storm, Deathbird has a guy smuggle her on to Hala, then immediately kills him, because she's too paranoid to believe he wouldn't tell someone she's there eventually (and the Supreme Intelligence already knows).
  • In Batman (Tom King) #86, two Joker henchmen in masks are burning several other Joker henchmen alive. As they leave, one of them comments to the other that they've proved their loyalty, and the other responds by shooting him in the head. He then phones the Joker to say all the henchmen who knew the plan are dead. The Joker replies "Not quite all", and his van blows up.
  • Blake and Mortimer: Han-Dié betrays Mortimer and had him captured to be delivered to Nathan Chase (actually a disguised Olrik). Han-Dié is also captured so he wouldn't leak the professor's kidnapping.
  • This is essentially the reason that The Boys haven't been brutally butchered by the ruthless Seven; the only reason they aren't dead is that they have even more damaging information on someone that The Seven fear more.
  • Button Man: Offing is standard procedure of dealing with anyone who knows too much about the killing game. Even Harry himself has tied up some loose ends of his own.
  • In Darth Vader: Dark Lord of the Sith, Darth Vader captures Jocasta Nu and one of the clone troopers with him insults her for being a Jedi. Jocasta then bluntly informs them that they're taking orders from a Jedi, and reveals Vader's true identity as Anakin Skywalker. Before they can react Vader then throws the clones out of the midair ship with the Force before turning on her.
  • The Incredible Hulk (1962): One of the first things the newly emerged Hulk tries to do is kill Rick Jones, simply because he knows he used to be Bruce Banner. Fortunately the sun comes up at that moment, immediately reverting the Hulk back to Banner, and the next time the Hulk emerges he decides to forgo killing Rick.
  • The Legend of Zelda: A Link to the Past (1992): Following Sahasrala's direction, Link heads for the Library to study the Book of Mudora, only to find it has been set on fire by soldiers. The boy alerts Link that the Librarian is stuck inside.
  • In The Punisher MAX, this trope drives a great deal of the series' plot. Frank is induced into taking part in a highly illegal and dangerous black ops mission in Russia on behalf of a cabal of corrupt generals. The mission ends with a lot of dead civilians (not Frank's fault), a lot of dead Russian soldiers (definitely Frank's fault), the largest, deadliest terror attack in Russian history (the generals' fault) and the mission's actual objective a total bust (To be fair to Frank, that last part was deliberate). Unsurprisingly, any information pertaining to the mission is sealed and the generals attempt to have Frank killed several times all of which fail and ultimately result in their deaths at Frank's hands.
  • Robin (1993): When Strader Pharmaceuticals realizes their ilegal experiments on Gotham's downtrodden have started to gain attention they hire mercenaries to kill and dispose of their surviving victims and those who are investigating the mysterious new deadly drug on the streets.
  • Dynamite's run on The Shadow:
    • In #8, a seemingly ordinary couple is killed. Their deaths are widely dismissed as just another murder, but the Shadow knows they chanced on something that the murderers were trying to hide.
    • In the Light arc, the first victim of that murderer doesn't match the profile of the subsequent victims. After some investigation, the Shadow concludes that he must have known something about the Light that she didn't want to get out.
  • This trope is what sets the whole plot of the first Sin City story "The Hard Goodbye" in motion, as Goldie is killed on orders from another character after she discovered his nasty secret habit. Another character dies after mistaking a death squad for honest cops and telling them everything.
  • Examples from Superman stories:
    • Superman: Exile: Morgan Edge has Intergang put out a hit on Clark Kent after information about the group gets out before he left. They end up murdering some poor schmoe breaking in the same time the hitmen did and it's Matrix's appearance as Clark does everyone calm down. At least until Edge's boss, Darkseid, takes matters into his own hands.
    • In Who is Superwoman?, the titular villain murders Reactron's ex-girlfriend so that she can't tell anybody Superwoman and Reactron are working together.
    • Later in The Hunt for Reactron, the titular villain murders a whole Metropolis Science Squad when they discover it was Sam Lane who blew the water reservoir up and Supergirl, Nightwing and Flamebird are being framed.
    • In The Unknown Supergirl, Lesla-Lar plans to help Lex Luthor kill Superman and then "accidentally" kill Lex while capturing him so he can't tell that the "hero" who avenged Superman was in fact Luthor's ally.
    • In The Killers of Krypton, Empress Gandelo orders her minions to find and kill Supergirl before her investigation uncovers she is responsible for Krypton's destruction.
    • In Starfire's Revenge, the titular crime queenpin gets her conman Derek Ames assassinated because she cannot trust him to keep his mouth shut about her secret plans, which he is aware of.
  • Tales to Astonish: When Vernon van Dyne accidentally summons the Creature from Kosmos, it exposits who it is and what it's going to do, then tells him he knows too much, and kills him.
  • In Top 10, pop star and former science-hero sidekick Glenn Garland is killed because he was going to tell the media about the illegal and repulsive actions of a group which he used to be a part of. The Vigilante from Venus also expressed concern that they were going to try to kill her before she went to trial, for fear that she would incriminate them in her testimony.
  • Vader's Quest: When Vader learns that the Death Star's destroyer is named Skywalker, several Bounty Hunters are in the vicinity, and he decides that Murder Is the Best Solution to silence them. One gets away and tells Palpatine, when they probably could have been kept silent if Vader had bribed them or just downplayed the importance of the information.
    Ban Papeega: Please, Lord Vader! I'll forget everything I've heard! I'll forget the name! Here, I've already forgotten all about Skywalker! I haven't even mentioned Skywalker just now! NO! [cue Gory Discretion Shot]
  • The conspirators in the Warlord of Mars volume Savage of Mars took extreme measures to silence Salensus Oll's concubines after one of them blew the whistle about who was behind the Green People's violent bursts. In fact, had her not warned the heroes about it, they would likely never had figured it out.
  • In Watchmen, two people knew the same thing:
    • One is killed because he knows the details of a plan, even though he had no intention of revealing it; he had told Moloch, who simply didn't understand what he heard and would be no threat to its success even if he did understand it.
    • The other (not Moloch) is killed because he knows the plan and is going to reveal it. His murder may have been pointless, though, because he'd mailed his journal to the "New Frontiersman". Whether anyone of importance would believe what that Conspiracy Theorist tabloid reports is unclear, though.
  • Wonder Woman:
    • Sensation Comics: Joel Heyday's mobster affiliates can't tell his triplet nieces apart, so kidnap two of them while trying to nab Tillie, who Joel intends to have write up a will bequeathing him the majority of what his mother is leaving to her in his will before murdering Tillie and his mother. As the other two have seen his accomplices he decides they have to kill the whole lot.
    • Wonder Woman (1987): When the mobster Danzik learned the officer set to testify against him was laid up in the hospital he sent one of his men to kill her before she could act as a witness against him in court. The addict who put her in the hospital in the first place happens to be trying to apologize when the assassin shows up and takes the bullets for her.
    • The Legend of Wonder Woman (2016): Alcippe is taken out by Antiope when Antiope realizes Alcippe has figured out too much of her traitorous plan.
  • As the lead geneticist in the Facility's attempts to clone Wolverine in X-23: Innocence Lost, Dr. Sarah Kinney knows everything about the X-23 project, particularly after Rice reveals that additional clones are currently in production, with the plan being to sell them to the highest bidders. After firing her, Rice decides to ensure her silence about the project by arranging to have X-23 kill her by contaminating Sarah with the trigger scent (that, and because he's a tremendous dick). Unfortunately for him, Sarah's final act is to turn X-23 loose against the Facility itself...
  • Yoko Tsuno:
    • Karl assassinated Ingrid's father because the latter has discovered the former's evil plans. Karl planned to drive his rich uncle insane with the Devil's organ, so he can inherit his wealth.
    • Leyton discovered that an alien creature was responsible for the discovery of antimatter and it controlled the base with its tentacles (which actually were its nerves). It killed him by crushing him to death.

    Fan Works 
  • In Advice and Trust, Rei wanted to tell Shinji and Asuka everything about her origins and NERV and SEELE's real goals, but Kaworu warned her that SEELE would kill them all if they found out that they knew too much.
  • Better Bones AU: Flametail drowns under the frozen lake due to supernatural interference from the Dark Forest breaking the ice since he'd managed to figure out too much about Tigerstar's plans. They try to kill his spirit before it can reach StarClan as well, but Tigerstar himself steps in to stop this from happening.
  • In the Animorphs fanfic City of Lost Children, Tom fears that if Jake suspects that something is wrong with The Sharing, he'll be made into a Controller, too. Of course, the readers know that Jake is fully aware of The Sharing's secrets.
  • In Hey Arnold: The Furnace, Arnold is murdered when Sid reveals that they murdered Stinky after one huge misunderstanding.
  • Kingdom Hearts: The Antipode: In the first instalment, the Coachman tries to kill Riku, Donald and Goofy when they discover Pleasure Island.
    I don't take well to trespassers. Especially meddlesome brats like you. You've seen far too much, boy. I thought The Heartless would do you in, but I see that you're a bigger pain than I would've imagined.
  • Played for Laughs in A MODern Man when Harry moves his future-selfs corpse and Draco spots him.
    Draco: W-was that a muggle?
    Harry: Of course not! That was a witness.
    Draco: To what?
    Harry: That matters even less than if he was a muggle. He thought he saw something, that was enough. You haven't seen anything today, have you, cousin?
    Draco: No! Not a thing! I gotta go!
  • In Pages Of Harmony, Twilight ends up kidnapping and killing Spike and Sweetie Belle because she fears they'll learn too much about her plans involving the Elements — the former because he hangs around the library and starts to get suspicious, and the latter because she witnesses Rarity being kidnapped.
  • The Power of the Equinox: After Brutus Meadows kills his wife in anger, Cheerilee comes to see why Scootaloo is missing class. When a bolt of flashing lightning reveals the blood and feathers in the dark hallway and stairs, she runs off to get help. Brutus, desperate to keep his crime a secret, chases after her with the intention of killing her.
  • Magnificent Kamen in Sailor Nothing allows no witness to escape to reveal the Masquerade. The fact that he's a Yamiko probably has something to do with that.
  • A recurring theme in The Shadow is Vader (or more recently, Luke) killing someone for knowing Luke's identity beyond "Vader's Apprentice". Most notably, Boba Fett tries to blackmail Luke with the fact he's Anakin Skywalker's son, threatening to tell Vader if Luke doesn't get him an unspecified amount of money. Just before killing him, Luke tells Boba that Vader is Anakin Skywalker.
  • Team 8. Kurenai is killed because she's just figured out and proven how to beat Itachi's Tsukuyomi. Overlaps with Dying Moment of Awesome.
  • Played with in In the Kingdom's Service. Blake fears that her knowing Jaune and Oobleck are in the Vale Secret Service might get her killed, though Jaune refuses to snitch on her and Oobleck reveals as he dies that he'd known for weeks. After Jaune resigns from VSS over their order to doom himself and his team to save Vale, he's slated for termination but it's later explained that the problem isn't what he knowsnote , but that he's got connections to both Ozpin and Cinder, neither of whom can be allowed to learn of the VSS and their actions.
  • The Unabridged Memoirs of Darth Plagueis the Wise:
    • Unlike Palpatine in canon, Plagueis decides that leaving the Trade Federation leadership alive after the blockade of Naboo, when they might reveal their connection to the Sith, is too risky. So he arranges to have Nute Gunray and Rune Haako assassinated as they're brought in to stand trial (Haako survives, though he does end up in a coma for years).
    • After Plagueis employs Zam Wesell's shapeshifting abilities in order to frame Dooku as Darth Sidious, he decides she's too dangerous a loose end and orders her to be eliminated.
  • In Winter War, Hisagi kills Iemura for discovering that he is a Fake Defector, even though they were (theoretically) on the same side and Iemura was offering his support because he didn't believe that Iemura could keep the secret. The guilt eventually drives the killer into Heroic BSoD to the point where his zanpakutou has to take over his body just to keep him alive.
  • In To Hell and Back (Arrowverse), the main tree characters were forced into working for the League of Assassins for several years before breaking free. They have kept their past actions from their families, but Amanda Waller knows everything about them. As Oliver Queen succinctly puts, "[She knows] too much". Unfortunately for them, Waller has made herself untouchable.
  • Kara of Rokyn: After Lex Luthor shows to them what he has done to Superman, villains Cyber and Starfire realize Luthor will kill them if he believes they might reveal his secret.
  • In Promise on the Festival Night, Kouta's father heavily suspects that Lucy has committed several crimes, such as fraud and murder (which she has). Kouta's father threatens to tell Kouta (as well as Child Services and the Police) about his suspicions unless Lucy stays away from his son. To be able to stay with Kouta without him finding out what kind of person she is, Lucy murders Kouta's father by pushing him in front of an oncoming train.
  • Safe Harbor has a non-lethal variant when King Frederic orders his guards to keep Varian contained so as to prevent him from revealing to everyone how much danger the black rocks pose to the kingdom.
  • Remnant's Bizarre Adventure: While most of Cinder's Stand users only know Torchwick, and if they have met her it was while she was in disguise, Red Hot Chili Pepper is an exception due to being tasked with spying on Ozpin, Ironwood, and Jotaro through Beacon's CCTV systems and having to report to her. As soon as Josuke beats him at the docks, Cinder torches Akira Otoishi before RHCP can reveal her name. She mentions to Roman beforehand that Otoishi is simply a Psycho for Hire who was planning to move on after that job, and she would have killed him even if he had succeeded in his mission.
  • Scoob and Shag: After he delivers his report to him, Mick kills Patrick to make sure that he can't tell anyone else about what happens in the future.
  • For the Glory of Irk: As we learn near the end of the story, the Control Brains assassinated Tallest Miyuki when she learned of their plans, and made it look like an accident caused by Zim.
  • In The Awakening of a Magus when Pettigrew is captured in a manner that doesn't allow Voldemort to drain his power, he orders him to be killed while in custody.
  • In with the Old, Out with the New has Kano kidnapping Cassie Cage mainly because she discovered the new location of the Black Dragon hideout, but also as payback for Sonya beating him down back in the refugee camp.
  • Played with in Misaligned Gemini when Prowl fears that Sideswipe may be targeted for learning that he was the subject of another of Sentinel Prime's governmental cover ups. Sentinel's final orders being to kill Starscream, his own former Head of Intelligence, only makes Prowl more worried for Sideswipe's safety and he tries to convince Sideswipe not to come to work the next day. Later, Sideswipe realizes that Getaway, a Spec Ops bot and one of Sentinel's top men, would have hunted down and killed him for knowing about the conspiracy if Sideswipe did not gain Getaway's curiosity by trying to establish contact with loyal Autobots in Kaon.
  • Another non-lethal variant in the Frozen (2013) fic Winter Has Come. The fic opens with Kristoff and Hans at Castle Black, the former having been sentenced to the Night's Watch after an undisclosed incident involving the royal family of Arendelle. Even Hans can't help but ask him what happened, but quickly drops the subject when it becomes clear that Kristoff does not wish to speak of it. Toward the end, it is revealed that Kristoff discovered Anna's sexual affair with her sister, Queen Elsa, who quickly used her powers to knock him out and then packed him on a cart destined for the Wall.

    Films — Animated 
  • Aladdin and the King of Thieves: Regardless of the fact that Aladdin is Cassim's son, Sa'luk quickly declares that Al is still an intruder
    Sa'luk: Blood or mud, the boy is an intruder, and we have rules about intruders. He has found our secret lair. He has seen too much. He must die. (turns to Abu and Iago) They must ALL die!
    Iago: DIE?! He's your son! I'm his friend! CAST A VOTE FOR MERCY HERE!!
    Sa'luk: Yes, Cassim, mercy would be so like you. Soft...and weak!
  • Fred in Big Hero 6 cites this trope as the reason why Yokai is trying to kill them after the heroes see him and his nanobots.
    Wasabi: Why's he trying to kill us?! (Rolls down his window to talk to Yokai) Uuuh, why're you trying to kill us?
    Honey Lemon: Let's not jump to conclusions. We don't know he's trying to kill us.
    (As she says this a car is launched at them)
    Fred: CAR!!!
    Honey Lemon: HE'S TRYING TO KILL US!
  • Monsters, Inc.: Mr. Waternoose says this as his reasoning for still going after Boo in the film's climax, and unfortunately for him, Mike gets it on tape.
  • NIMONA (2023): The Director tries to pull this on who she thinks is Ambrosius after revealing to him that she was the one who killed the queen. Unfortunately for her, "Ambrosius" was actually Nimona in disguise, with the whole thing being a setup for the Director's Engineered Public Confession.
  • Lampshaded in Scooby-Doo and the Alien Invaders, where the villains say this as they prepare to kill Fred, Velma, and Daphne. Fred grumbles "That's always our problem..." in response.
  • Nicodemus inverts this in a discussion with Mrs. Frisby in The Secret of NIMH; instead of using it as an excuse to die, he utilizes this fact as a reason to survive by leaving their colony. "My child, we can no longer live as rats... we know too much." In this case, the rats have become so intelligent that they've developed morals against stealing from the local farmer to survive and must form their own civilization away from humans.
  • In Wendell & Wild, after Father Bests brings up the fact that he was the one who vouched for the Klaxons after the brewery burned down in exchange for them continuing to fund his school, Irmgard Klaxon kills him so he won't get any ideas about possibly going to the police about what they did.
  • Zootopia: Emmitt Otterton was on his way to talk to Mr. Big and was "silenced" when Doug shot him with a serum pellet while he was on route. According to Manchas, Otterton wailed about "Night Howlers" before fully succumbing to savage madness.

    Films — Live-Action 
  • '71: Captain Harris and Sergeant Lewis decide that they need to kill Gary after he sees the bomb in the pub.
  • 8 Women: Chanel figures out the truth behind the murder about halfway through. However she gets shocked into silence by a mysterious gunshot before she can say anything (she doesn't actually get shot, so she doesn't die; she's just conveniently out of commission until the end).
  • Ace Ventura: Pet Detective: Lois Einhorn/Ray Finkle murders Roger Podacter when he discovers her true identity during a sexual encounter.
  • Subverted slightly in Adventures in Babysitting — one of the kids had taken a Playboy magazine that could get the crime boss put away, and the presumption the criminals made, of course, was that the kids had read it, plus the fact that they'd met at all meant they knew too much. The magazine was returned, and the crime boss' underling resigned, knocking him out along the way.
  • American Beauty: Col. Fitts kills Lester to make sure he doesn't tell anyone that he's gay.
  • Andhadhun:
    • Mrs. D'Sa having seen who entered the Sinhas' apartment and in which order makes her able to contradict Simi's account of the events. In addition, she says that she would be able to identify the unknown man who entered first (Manohar), which would reveal the truth. Consequently, Simi decides to kill her before she can go on record.
    • Akash knowing about the murder of Mrs. D'Sa. Simi decides to ruin his credibility as a witness by blinding him for real. Manohar decides that that isn't enough, and goes to kill him instead.
  • Deconstructed in Angel Has Fallen. Wade murders FBI Agent Thompson when she inadvertently reveals to him she knows that he framed Mike Banning for trying to assassinate President Trumbull while trying to question him. However, killing her doesn’t magically get rid of the evidence and in fact makes it so that he now has a limited time to kill President Trumbull since the FBI is rapidly closing in.
  • Apt Pupil: Dussander starts putting on his SS uniform even when Todd is not around to blackmail him. Unfortunately, a homeless person sees him through his window. Dussander then kidnaps and holds the man captive in his basement, later coercing Todd to murder him.
  • Back to the Future Part II: Old Biff gets the idea to back to the past to give his 1955 self the Gray's Sports Almanac, so he'll be rich in the future. He also tells him that either a kid (Marty) or an old man (Doc) will come around asking about that book, and to kill them if they do so. Indeed, Present Biff-A tries to shoot Marty down in his own office after he finishes his exposition, and Marty barely escapes with his life.
  • In The Bourne Supremacy, Jason Bourne learns that his first target as a Treadstone agent was Vladimir Neski, a Russian politician who'd been killed before revealing that businessman Yuri Gretkov was using stolen CIA funds to buy up Russian oil leases.
  • In Breakheart Pass, Capt. Oakland, Lt. Newell, and the fireman are all murdered because they discover too much about the conspiracy and what is really going on at the fort.
  • In Captain America: The First Avenger, Col Phillips warns a captured Zola that Schmitt will see him this way. Eventually, he does get offed in the far future for knowing too much... because he orchestrated half the conspiracy himself, accepting his fate to take Captain America with him.
  • In Captain America: The Winter Soldier, a maid walks in on her employer briefing the Winter Soldier, and is regretfully shot dead. Zola reveals that Howard Stark had an 'accident' before he could reveal Hydra's takeover of S.H.I.E.L.D.; the video of the Winter Soldier executing Howard and his wife is shown in Civil War.
    Romanov: That's impossible, S.H.I.E.L.D. would have stopped you.
    Zola: 'Accidents' will happen.
  • In a movie about the presidential candidate Luis Donaldo Colosio's assassination in Tijuana called Colosio El Asesinato, the main character is a police officer who works undercover and is asked by the president's former brother-in-law José Francisco Ruiz Massieu to investigate the murder. After a series of investigations, he concludes that the very same party killed Colosio. At the same time, someone is killing everyone involved with the case and murder, including the murderer and anyone who dares to seek the truth. As a result, the main character gets killed in the end as well as his pregnant wife, his partner, the police chief in Tijuana, and Ruiz Massieu, all because of this trope.
  • The Conspiracy kicks off when the subject of a conspiracy theorist documentary goes missing, and Jim is killed and Aaron threatened into silence after being found out at the Tarsus Club.
  • In Cube 2: Hypercube, this appears to be the entire reason why almost everyone was thrown into the hypercube to die, as they all have some sort of connection to the hypercube's controllers. Except for Sasha, who it's revealed went inside willingly to hide, and Kate, who's an operative sent in with a mission. It's also why Kate's superiors summarily execute her when she returns with her mission accomplished.
  • In Dark Side of the Moon, an overzealous CIA officer sends assassins after everyone involved in a Moon-Landing Hoax.
  • Inverted in Diamonds Are Forever concerning the diamond smuggling ring. When one of your own passes you fake diamonds, he knows too much about the circumstances to die. This is demonstrated when Shady Tree rescues James Bond (who had assumed the identity of Peter Franks, a fellow diamond smuggler who Bond had killed) from a retort to question him about where he hid the real diamonds, only for Bond to use leverage against him to the tune of $50,000 ("You bring me the real money, and I'll bring you the real diamonds."), and then Zig Zagged when Albert R. Saxby reminds Wint and Kidd that they "didn't get the real diamonds. So we need Tree, alive." Wint and Kidd remark on how "that's most annoying" because they had already cut Tree down, as revealed when Bond shows up in his dressing room.
  • In Dick Tracy Meets Gruesome, Dr. Learned panics when she learns that Tracy knows that she stole the emperimental formula from the university lab. Dr. Thal decides to get her out of town and sends Gruesome to pick her up and take her to his cabin on the lake. However, when Gruesome arrives at the meeting point, he just guns her down, then returns to Thal and explains that she knew too much about their operation and he couldn't risk her falling into the hands of the police.
  • In Dredd, a paramedic informs a corrupt Judge that his assessment of the situation is wrong; it's not a gang war, just Ma-Ma's gang vs. the Judges. When asked if he'll testify to that he gives the wrong answer.
  • In Drive (2011), a gangster uses a crew of low-level criminals to rip off a Mafia boss with the intent to later kill them and take the money for himself. When the plan blows up in his face, he and his partner decide that everyone involved Knows Too Much and must die so the Mafia never finds out who was really responsible. Ironically, the only survivor of the crew actually does not know anything and was about to leave town.
  • All over the place in The Fourth Protocol, about a Soviet plot to set off a nuclear bomb outside a US airbase in Britain and Make It Look Like an Accident. The implications of this plan being exposed are so serious that the KGB sleeper agent and the scientist who assembles the bomb are set up to be killed. The film takes this up to another level for dramatic purposes — it opens with traitor Kim Philby (who planned the operation) being shot, the man who shot Philby getting his neck broken, and an innocent bystander who walks in on an exchange of a smuggled component gets stabbed.
  • In Frankenstein 1970, Victor murders his old family retainer Schutter after Schutter discovers his secret laboratory.
  • Grandmother's House: When David exits the basement after finding the woman in the blue dress tied up in the fridge down there, he's caught by his grandfather, who is now sure he saw her. As a result, much of the next scenes involve David hiding from his grandfather, who's wielding a shotgun, intent on killing him to keep the secret.
  • In Green for Danger, Sister Bates claims to have evidence that Higgins was murdered, but before she can show anyone, she is stabbed to death herself by someone in a surgical gown.
  • Alfred Hitchcock was fond of this trope, which he used as the key plot element in films such as The Man Who Knew Too Much, North By Northwest, and Saboteur.
  • After Rick shows his girlfriend Angela Bancroft's secret museum in Horrors of the Black Museum, Bancroft decides that Angela knows too much and hypnotizes Rick into murdering her.
  • It's pretty strongly implied that the "villain" of The Hunted (2003) was just acting in self-defense, pursued by government assassins over his past black-ops experience.
  • I Come in Peace: Larry's FBI boss tries to kill his subordinate after Larry hands over the energy weapon which he retrieved from the alien cop, but Larry's local partner Jack saves him by shooting the guy first.
  • The Internecine Project (1974). A former intelligence agent is being promoted to government advisor, so he plans to have four colleagues who know about his past 'dirty tricks' work kill each other off.
  • In Lethal Weapon (1987), Riggs is tortured by the bad guys to find out what he knows about their impending shipment, which is nothing.
  • Mushnik in Little Shop of Horrors, adapted from the stage musical. This trope did not apply to the original film.
  • The Man with One Red Shoe (the American remake of the French The Tall Blond Man with One Black Shoe) has the scheming deputy head of the CIA trying to frame the actual head so that he can have his job. The head knows this and lets slip that someone who can foil this plan very simply will be arriving at the airport. He then sends his aide to meet any random person at the airport, so that the deputy and his men will follow them and try to find out what he knows. The aide picks a rather head-in-the-clouds musician, who's wearing a pair of mismatched shoes because of a practical joke.
  • The Hero in Marathon Man is one of the actually-know-nothing kind.
  • In The Monster Maker, Dr. Markoff decides that Maxine has to die after she accidentally learns the true nature of his evil scheme, as she is now the only one to know both his plan and his true identity.
  • In Mortal Engines, even though Tom doesn't comprehend what Hester said to him, it's enough for Valentine to kill him rather than risk his secret getting out. Justified as he is a Villain with Good Publicity and is involved in something even the city's rulers don't know about.
  • Mulholland Falls: Alison was murdered because she had uncovered and recorded illegal nuclear testing on U.S. military personnel at the atomic testing site.
  • Murder by Decree;
    • Polly Nichols, Liz Stride, and Annie Chapman were killed for knowing what Mary Kelly told them about the child.
    • Makins the Citizens Committee Member for making the 'Juwes' message and telling Holmes to check on it.
  • Robert's justification for killing Leroy and Destiny in Mystery Team.
  • In No Way Out (1987), Nina is a friend of Susan Atwell, mistress of Secretary of State David Brice. When Brice kills Susan, and his aide Scott realizes Nina knows about Susan and David (he's trying to cover up the crime by pretending a Russian spy code-named Yuri did it), he sends minions after her. Tom, who works for Brice, and who was involved with Susan, realizes this and goes to the shop Nina works at to warn her to escape so she won't get killed. This seems like a Big Damn Heroes moment, except what he's really doing is trying to keep Scott from finding out he's really The Mole Scott is pretending to look for.
  • In Once Upon a Time in Mexico, Sands is captured after he discovers part of Barillo's plan that he wasn't supposed to. It ends badly for him, though not fatally.
    Sands: I feel its only fair to warn you that killing me is crossing the line and you will have every single Marine from here to Guantanamo Bay up your keister, mister, so just know that.
    Barillo: Fortunately for you, nothing you did is worth dying for. You have only seen too much. We are going to make sure this does not happen again.
  • In The Phenix City Story, the gangsters set out to kill Ellie, the sole witness to the assassination of Patterson.
  • Governor Swann is killed in Pirates of the Caribbean: At World's End because he finds out what really happens when someone stabs Davy Jones' heart.
  • In Power of the Press, Bradford rallies to the defense of Purvis and posts a reward offer for information leading to his exoneration. A "newsie" comes forward with information that will clear Purvis, but Oscar Trent, one of Rankin's men, throws him down an elevator shaft before he can make a deposition.
  • The President's Analyst is privy to the innermost thoughts of the President — when the strain of the job becomes too much he skips town, pursued by foreign agents wanting to tap his mind, and domestic agents who, because he knows too much, want to bring him in or kill him.
  • The main action of the Brandon Lee movie Rapid Fire starts when Brandon's character witnesses a bad guy in the act of taking out a rival.
  • Red (2010) starts when a commando team tries to assassinate retired CIA agent Frank Moses. He quickly realizes that someone is trying to kill him because of something he knows, but because he doesn't know what it is and they don't know who he might have told, they're targeting people he's been in contact with as well so he's got to find his old friends before they can be attacked as well.
  • Relative Fear: Scatterbrained Senior Earl is killed shortly after rambling that he saw how Manny really died.
  • Return of the Jedi: The speeder-bike chase happens when a group of scout troopers find the rebel strike team (thanks to Han stepping on a dry twig) and Luke and Leia are forced to chase down two fleeing scouts (plus two more who join the chase).
  • In Serenity (2005), the Operative is sent after River because she picked up the secret of Miranda, which has been buried for twelve years, from the heads of top members of the Alliance's Parliament who came to the Academy to see her. The nature of the secret in question means that Parliament wants more than anything to keep it buried, even if it means River must die. This is a perfect example of the variant, since River was totally crazy, so she couldn't have communicated what she knew to anybody who could do anything about it. The Operative coming after her and the crew compelled them to find out the truth.
  • The Hong Kong action movie Sha Po Lang (known in the US as "Killzone") kicks off with the murder of a witness ordered by a Triad crimelord so that his testimony could not be given and the crimelord would be set free. This sets four cops against him, all with their own reasons for wanting to take him down.
  • Shark Attack: It turns out that Steven's friend was murdered and dumped into a shark-infested lake because he was starting to uncover the bad guy's plan.
  • Snakes on a Plane: The catalytic event for the eponymous serpents upon the aircraft.
  • In Some Like It Hot, the two main characters accidentally witness a St. Valentine's Day Massacre-like gang shooting in a parking garage. They know their lives are not worth plug nickels, because they know too much, so they try to get on the next train out of town. The only train available is one that is transporting an all-women band to Florida. They're musicians, so they dress up as women and get jobs in the band so that they can board the train and escape the mobsters. Hilarity ensues.
  • Spider-Man: Far From Home: Once Spider-Man figures out the Big Bad's identity and plan, he decides to have him and anyone he told killed. For Betty, this is "She Might Know Too Much", while for Flash it's "He Is Standing Next To People Who Know Too Much".
  • Star Trek III: The Search for Spock: When Valkris remarks that the information she's transmitting to Kruge will be "useful" (thus revealing that she knows its contents), Kruge replies that the situation is "unfortunate" and destroys the ship she's on.
  • Star Trek VI: The Undiscovered Country: The two crewmen who killed the Klingon Chancellor are killed in turn by another conspirator, Lt. Valeris. On finding the bodies, Kirk grimly notes "First rule of assassination: Kill the assassins."
  • In Teenage Mutant Ninja Turtles (1990), Shredder orders his Foot Clan to kill April O'Neil when she begins to dig too deep into his group.
  • These Are the Damned. Freya Neilson isn't happy about the secretive nature of her boyfriend Bernard, who is involved in a top secret government project, but he warns her that knowing anything about his work could put her life in danger. By the end of the movie she's seen too much to be let go, but Bernard offers her the chance to join him in his work. She finds it so abhorrant however, she chooses to die at his hand instead.
  • Averted in The Third Man. After Harry Lime makes an Implied Death Threat during his motive speech in the Ferris wheel, Holly Martins tells him that the authorities already know that he's Not Quite Dead, so killing Holly wouldn't change anything.
  • In Tragedy Girls, when Jordan finally catches wise to Sadie's true nature, she hangs him. Though considering how the film ends with Sadie and McKayla massacring the entire prom, he was probably screwed either way.
  • Valentine: During the third act, Ruthie Walker winds up in the same room as the Big Bad while he's Disposing of a Body and this pretty much marks her for death.
  • The Vindicator: When Carl confronts his boss Mr. Whyte about his suspicious funding cuts, the latter sends an employee to rig an explosion in Carl's lab to silence him while making it appear accidental.
  • Woman on the Run: The whole plot of the film is Eleanor trying to find Frank who has run away from a mobster who knows he witnessed his murder of an informant. And the killer stops at nothing to find him.

  • A KGB agent is questioned by his superior: "How much is 2 plus 2?" — "Four." — "And how much is 3 times 5?" — "Fifteen." — "And how much is the square root of 9?" — "Three." At the moment, the superior draws his gun and shoots the agent. "Comrades, I had to neutralize him, he knew too much!"

  • Syme in Nineteen Eighty-Four lauds the principles behind Newspeak to Winston, explaining in great detail how it helps the Party perfect its control over the general populace. Despite being thoroughly loyal to the Party, he is eventually made an "unperson" due to this understanding. A fate Winston himself is able to see coming, predicting that Syme will be "Vaporized" several chapters before it actually happens.
  • 20,000 Leagues Under the Sea: This is the reason why Arronax, Conseil, and Ned Land will remain prisoners of the Nautilus and cannot come back to Civilization. Ever. (Captain Nemo lets them abandon the Nautilus and explore land, but is always in uncivilized shores). Captain Nemo explains:
    "... You came to surprise a secret which no man in the world must penetrate — the secret of my whole existence. And you think that I am going to send you back to that world which must know me no more? Never! In retaining you, it is not you whom I guard — it is myself."
  • In Alternate Routes, the villain's minions are out to kill the protagonist because he accidentally overheard something that, while meaningless in itself, might have led him to dig deeper and uncover the villain's plan. (With the effect, inevitably, that he winds up uncovering and defeating the villain's plan in self-defence.)
  • Animorphs:
    • According to Temrash's memories in The Capture, Tom initially joined The Sharing because a pretty girl he liked was a member. During one meeting, she went off to meet with other Yeerks. Tom, thinking she was sneaking off to see another guy, followed her and saw Visser Three in Andalite form, and for this was captured, dragged off to the Yeerk pool and infested.
    • Later on in the series, Visser Three makes David's parents into Controllers after he and a bunch of Hork-Bajir storm their house.
    • The main characters consider this during the David Trilogy, when the eponymous character turns against them. It makes them pretty uncomfortable, though in the end, they decide on an even more extreme solution.
  • The Beginning After the End: In the distant past, Kezess Indrath, the ruler of the Asuras, orchestrated the genocide of the Djinn out of jealousy for their ability to control aether. He and his clan ended up covering the atrocity that they committed, obfuscating its true nature to the rest of the Asuras. As such, most of the Asuras do not know what really happened to the Djinn, and those who wanted to find out the truth wound up being covertly dealt with on Kezess's orders. Even whole clans on the Great Eight are not safe. Mordain Asclepius, once a close friend to Kezess, stood up against his former friend when he was about to order the genocide, which led to him and his clan being banished from Epheotus. A similar fate befell Agrona Vritra and his clan, who uncovered the truth through their study of the ruins the Djinn had left behind. Unlike Mordain, Agrona took his banishment far more severely, as it led to him instigating the Divine Conflict that ravages the setting.
  • A short story in The Best in Chess revolves around a cobbler who claims to have discovered an unbeatable chess opening, thereby rendering all Chess theory — and the game itself — obsolete. A chessmaster reassures him that there's still a way to defeat it, but then plunges a chess bishop into the cobbler's back.
  • The Black Arrow: Sir Daniel Brackley murdered Harry Shelton, heir of Tunstall, and obtained guardianship of his minor son Dick to hijack his inheritance. Several years later, when Dick's suspicions are raised and he starts making questions about his father's death, Sir Daniel decides to murder him before he discovers the truth.
  • In A Brother's Price, the protagonists find the corpse of a man who likely died from blood loss after his tongue was cut off. They conclude that the women who killed his family and kidnapped him wanted to keep him around (men have Gender Rarity Value in the setting), but didn't want him to be able to talk, and were too incompetent to silence him without killing him. Later on, one of Jerin's kidnappers advises her sisters to not talk too much in front of Jerin, as she would like her future husband to have a tongue.
  • The Cat Who... Series: One of the victims in book #24 (The Cat Who Went Up the Creek) is a nature photographer who found signs of illegal tree and gold prospecting in the Black Forest Conservancy, and is shot to prevent him from telling anyone.
  • A case of this kicks off the Nelson De Mille novel The Charm School when the KGB silence a tourist who blundered into evidence of the eponymous school. Ultimately, the US government also decides to hide the existence of the Charm School — and the American POWs who staff it — through even more drastic methods.
  • If you're a character in an Agatha Christie novel, don't ever try to blackmail a murderer if you want to live to the end of the novel. And if you know anything that might have any relevance to the murder whatsoever, go immediately to Miss Marple or Hercule Poirot and tell them everything, even if you aren't certain that what you know is important. Under no circumstances should you hint that you know something but fail to say what it is. Characters who have found this out the hard way include:
    • Angele Blanche from Cat Among the Pigeons, a would-be blackmailer.
    • Louise Bourget of Death on the Nile, another would-be blackmailer, along with Salome Otterbourne, who witnesses Louise's murder and goes to tell Poirot, invoking His Name Is... before being shot dead by the killer.
    • Joyce Reynolds, the 13-year-old schoolgirl from Hallowe'en Party (1969). She tries to use her knowledge of a murder to her benefit. Instead, the murderers have her killed, drowned in an apple-bobbing tub. And what makes this worse is that it's not even her knowledge, really; she's overheard the child who really does know about the murder talk about it and has tried to pass it off as her own knowledge for attention. Later in the story, a second victim - Joyce's younger brother Leopold - figures it out, tries to blackmail the killer, and meets much the same fate.
    • All the victims in A Murder Is Announced, although the first had no idea that he knew anything of value.
    • Amberiotis of One, Two, Buckle My Shoe knew about Alistair's Blunt bigamy, a fact which he discovered from Ms Mabelle Salisbury Seale, who is friends with his secret wife. Both were killed to hide the scandal from the public.
    • Both Carlotta Adams and Donald Ross from Lord Edgware Dies were killed because they knew that the "Jane Wilkinson" at the dinner was an imposter: Carlotta because she was the imposter, and Donald because of a social gaffe made by the real Jane at another lunch party.
    • Other characters who "knew too much" include Mrs. Upward from Mrs. McGinty's Dead, Miss Johnson from Murder in Mesopotamia and Esa (the sixth victim) from Death Comes as the End — as well as the principal murder victims in Three Act Tragedy, The Murder of Roger Ackroyd, Cards on the Table, Evil Under the Sun, and A Caribbean Mystery.
    • An example of the second variant comes in Why Didn't They Ask Evans?. Bobby Jones witnessed the death of a man who stumbled and fell off a cliff, then tells a woman claiming to be the man's sister that his last words were "Why didn't they ask Evans?" This is enough to convince the conspirators that Bobby has to be killed, which is in turn enough to convince Bobby that the man was murdered, "Evans" knows something important, and he should investigate...
  • The Chrysalids: A heroic version. The protagonist is one of a number of secret telepaths living in a dystopian society where anyone discovered to have a mutation or genetic deviation is tortured or killed. His supportive uncle and Secret-Keeper murders a nasty character who has discovered the group's secret from his wife (who’s one of the telepaths) and is on the point of exposing them, in order to save them from almost certain death. Unfortunately, this causes the wife to mistakenly blame the other telepaths and leave a letter exposing them when she hangs herself, but because her sister is able to get it before the letter is opened, no harm comes to the telepaths at that point.
  • Chrysalis (RinoZ): The Legion does not force any candidate to go through with the horrifically painful process of becoming a full Legionary. But they don't allow anyone to walk away with knowledge about that process, either. If someone wants to back out, all they have to do is volunteer and receive a quick death instead.
  • Darth Bane: By the time of the third book, Bane and Zannah have this as standard operating procedure for anyone who might have even the remotest suspicion that they are not simply a pair of eccentric businesspeople with an interest in old Sith artifacts. Or who might sniff to close to their affairs, even if they have no idea what they're sniffing at, as one unfortunate smuggler and a bartender on an out-of-the-way planet learn first hand.
  • The Diabolic: Sidonia cries to her teacher about how her family is sending Nemesis off to court instead of her. The teacher says "that's treason", and Nemesis kills her. She tried to pull her away from Sidonia so that she didn't have to watch, but ultimately did it without a second's hesitation.
  • The climax of Dinner at Deviant's Palace is a No, Mr. Bond, I Expect You to Dine situation with a bunch of the villain's underlings joining the villain and the hero for the eponymous dinner. When the hero is shown in, he addresses the villain by his true name, and the villain notes that several of the dinner guests have now been let into a secret they can't be allowed to leave with and will have to be killed when the dinner is over. As the conversation continues through the hero's other discoveries about the cult, the villain continues to casually note whenever another revelation has doomed a few more guests, until they get to the real reason the villain's cult bans music, at which point the villain announces that the list now includes every single person in the room.
  • In Dragon Bones the protagonists are told about a man who got tortured and very nearly killed by the villains, who suspected he knew too much. He faked being masochistic and suffering amnesia in order to avoid this fate. (He pretended to have forgotten about the torture and be only worried someone could find out that he sometimes pays women to inflict pain on him.) It worked, probably due to Wrong Genre Savvy villains who thought they were in a detective novel, where leaving the potential witness alive would indeed be cleverer.
  • In Duumvirate, anyone getting too close to certain truths is most commonly fed misinformation, with options for inflicted insanity, death, and acquisition.
  • The Elemental Trilogy: The Bane kills hundreds of his soldiers when Titus reveals his usage of taboo sacrificial magic.
  • The Enemy by Desmond Bagley. A British scientist runs to Sweden after an attack on a member of his family. A Government Agency of Fiction follows him but only finds the scientist and his bodyguard killing time there. In order to shake things up, they pretend to be a KGB team conducting a ridiculously inept tail, but this backfires badly when the bodyguard responds by shooting dead the man he's guarding after they're cornered. The rest of the book is spent finding out what was so important about the scientist he had to be killed to prevent him from falling into enemy hands.
  • Flawed: After Craven gives Celestine a sixth brand, he does whatever he can to cover it up. Any staff that saw it mysteriously cannot be reached, while Carrick is forced into hiding.
  • The Fragility of Bodies: The Cartel tends to do this to people who get too close to uncovering their Blood Sport. They usually just bribe people, which works well in the poorer areas of town. But people who are determined to expose the truth, such as Rafa and Verónica, are marked for death.
  • In Dan Abnett's Gaunt's Ghosts:
    • Traitor General is a rare heroic example, with a kill team being formed to hunt down and eliminate the eponymous villain before he spills too much of what he knows to his new Chaotic masters.
    • The Armour of Contempt: Ludd interrupts a No-Holds-Barred Beatdown intended to kill Merrt. The man ordering it assures him that the body would never be found here, and offers a bribe. Ludd says he could report it anyway, and the man admits he knows too much to live. Fortunately, Ludd had backup, even though Hark had been distracted for a minute before.
  • In Douglas Coupland's Girlfriend In A Coma'', Karen, the eponymous character, believes this was why she went into her coma in the first place — she caught a glimpse of the future, and it wasn't pleasant.
  • Throughout Harry Potter and the Order of the Phoenix, Kreacher the house-elf serves as little more than a nuisance to anyone in 12 Grimmauld Place (namely Sirius), but they can't free him with clothes because he knows too much about the Order (as long as he is owned, he is actually incapable of violating his owner's orders).
  • A Hole in the Fence: Subverted. When Basile reveals to Grisón that some people discovered the secret of the Forbidden Zone, Grisón asks warily what happened to them. When Basile answers "Absolutely nothing", Grisón becomes flummoxed and asks why nobody explains why the Zone is forbidden so everybody knows why they should stay away. Rather than answering, Basile encourages Grisón to keep investigating...but without making questions. Making questions is a bad idea.
  • Honor Harrington: Defied in Crown of Slaves. After Thandi Palane resigns from Solarian Commodore Luis Roszak's staff, his XO suggests eliminating her on this basis, but are warned away by the fact that she is connected to knowledgeable and hardened killers (read: Victor Cachat, Anton Zilwicki, and Jeremy X) who would take bloody vengeance, compounding the fact that the person who knows too much is the one they would go to for assassinations in the first place. More to the point, the Sollies are fairly certain that Thandi will keep her mouth shut, and they generally liked her anyway.
  • Jaine Austen Mysteries: In Death of a Trophy Wife the killer lures Bunny's maid Lupe to a "job interview" to keep her quiet about their identity, after Lupe figured out who was really supposed to die that night, but couldn't report it due to her immigration status. When they have Lupe where they want her, they bash in her head with a tire iron and throw her in a dumpster. Thankfully, Lupe survives.
  • Undoubtedly inspired by the assassination of Von Papen (see Real Life), Ian Fleming had two SMERSH assassins fall victim to this trick in his first James Bond novel Casino Royale.
  • In Kill Decision, after Strickland discovers that someone is stealing his team's code and gathers them, the villains have them killed before they can investigate further or tip anyone off.
  • In Moonlight Becomes You, it's revealed that Nuala was murdered because she found a bell on her friend Constance Rhinelander's grave, which made her suspicious enough that she looked into the other recent deaths at Latham Manor and realized they may have been murder victims as well, as they all had bells on their graves and died within weeks of each other. The killer later attempts to murder Maggie because she had realized the same thing as Nuala.
  • The Mote in God's Eye. After the three midshipmen crash land on Mote Prime, they wander around for a while and make a number of discoveries. The Motie decision makers decide to kill them to keep them from telling the other humans what they've found out. And it plays out the other way, too. The humans are about to be captured, but they decide that they know too much about human technology to allow themselves to be taken prisoner — so they kill themselves.
  • In The Numair Chronicles it's heavily implied that Faziy was killed to prevent her from revealing too much about Prince Stiloit's death. Arram suspects that Stiloit's death was premeditated rather than caused by an errant storm and that Faziy had something to do with it, given her connection to the lightning snakes. His masters and friends advise him to keep this to himself lest he meet Faziy's fate.
  • Subverted in A Piece of Resistance, a novel by Clive Egleton set in a Soviet-occupied Britain. A resistance leader is captured, and the protagonist is told by his superior that he must be freed or, failing that, killed as he knows the identity of hundreds of Resistance members. It turns out the only person he knows is the superior, who's just protecting his own skin.
  • Pretty Little Liars: Hanna gets hit by a car when she recognizes A's number in Perfect.
  • In Qualia the Purple JAUNT blows up an entire plane in order to dispose of Hatou and Yukari's family, who were traveling to America because they were prying into the incident that resulted in Yukari's death.
  • Safehold:
    • This is a constant danger for the protagonists, as their knowledge of Safehold's status as a Lost Colony in Medieval Stasis would be blasphemous to the average person. They have to be insanely cautious about who they let in on the knowledge. Those people are also told if they don't work it out themselves, that if there's any danger of betrayal they'll be forced to take measures.
    • A specific instance occurs in the third book, By Heresies Distressed when an attempted assassination is foiled by the arrival of Merlin, who is supposed to be hundreds of miles away in a whole other country. Merlin then proceeds to kill every enemy there to prevent anyone from talking about his arrival.
    • In later books, the protagonists start using Merlin's cave complex deep in the mountains to house such individuals as a compromise. Those still deciding where they stand, or who can not bring themselves to become allies of the protagonists, can be kept there in isolation and physical safety, unable to be a risk to the Inner Circle, and allowing the Inner Circle to avoid being any more ruthless than absolutely necessary. They even offer their "prisoners of state", the option of cryo-sleep so they can awake after the conflict has ended if they so wish.
  • Brandon Sanderson:
    • The Emperor's Soul; Shai knows she's going to be killed after she is no longer useful to her captors in part because she could blackmail them with the fact that the Emperor was almost killed and they resorted to forbidden magic to fix and conceal this. She doesn't actually want to blackmail them, but they won't believe that.
    • Used as well in Sixth of the Dusk, where Dusk originally thinks this is why Patji is trying so hard to kill him, even when he's trying to drive intruders from the island. He knows the secret of the island's heart, the fact that every Aviar must migrate here and eat a special fruit filled with worms. Otherwise, they cannot grant a talent.
  • In Seven Years Awesome Luck, Trick witnessed a corpse being added to someone else's grave while he was still a cat, but didn't understand nor much care about its significance. When he later passes the information on, though, it starts attracting unwanted attention.
  • One of the original Sherlock Holmes stories, "The Adventure of the Engineer's Thumb", features a counterfeiter gang which doesn't include a repairman for their heavy equipment, so once a year or so, they are forced to bring in a disposable one.
  • A Song of Ice and Fire:
    • Bran sees Jaime and Cersei having sex and is then pushed out of a tower for it. During the ensuing coma, he's attacked by an assassin. We later learn that the assassination attempt is a subversion — he was attacked because Joffrey wanted his father's approval.
    • Jon Arryn learned about Jaime and Cersei as well and promptly died under suspicious circumstances. Interestingly, this is also a subversion — he was killed because Petyr felt like sowing some discord.
    • Petyr also has a habit of doing this, murdering Ser Dontos, whom he used as a catspaw in order to smuggle Sansa Stark out of King's Landing, and his accomplice in Jon Arryn's murder, Lysa Tully.
  • Lampshaded in a Star Trek Expanded Universe novel in which a friend of Captain Kirk learns of the existence of Section 31 — and then dies in a Teleporter Accident before he can tell Kirk. Upon learning of this, Spock muses that "the overly knowledgeable had become exceedingly short-lived".
  • In Striptease by Carl Hiaasen, this drives much of the main plot as characters discover a Congressman who beat up another patron at a nudie bar. They're hoping for some blackmail, but the Congressman's people have other ideas. A purer example is mostly in the background — three migrant workers are hired to murder one character, sent back to Jamaica afterwards, and it's implied that a fatal accident will be arranged for them there.
  • Morgause's spy in Sword of the Rightful King kills (at least) two people directly and one indirectly because they know his face and some part of his plans, meaning they might blow his cover.
  • "Talma Gordon": Cameron's father was killed by Captain Gordon after helping him bury his treasure to keep the location secret. Cameron notes that this was a custom among pirates.
  • In Updraft, this is why the Singers executed Nat's father; he knew that Singers possessed knowledge of how to safely navigate at night, which would be very useful for non-Singer fliers. Even if the Singers had been prepared to share that particular technique, people would wonder what else the Singers were hiding... and would now be better able to discover just that, since night would no longer cover Singer activities which people would get really angry about.
  • In Warrior Cats, this happens a few times:
    • In the first book, Ravenpaw witnesses Tigerclaw murdering one of their Clanmates, Redtail, in the hope of getting Redtail's job. Tigerclaw suspects he knows something, so he sends Ravenpaw on dangerous missions, clearly hoping that he'll get killed.
    • In the eighth arc, A Starless Clan, after Frostpaw has a vision that Reedwhisker was murdered by one of their Clanmates (though she's not sure who), she gets attacked by an unknown assailant and left for dead. Her attacker turns out to be Splashtail, the cat who murdered Reedwhisker.
  • One of Luis Fernando Verissimo's chronicles plays with this, being about a man who calls someone else on the phone by saying "I know everything", essentially blackmailing them into doing what he wanted without ever saying what he knew about. He began doing this to other people and managed to move up in life as a result. However, things escalated to the point the man was cornered by hitmen at his beach house and murdered... because of this trope.
  • After Cole Matthews raids a store, he brags that he committed the crime to the whole school. One of his fellow students then does what any sane person would do: file a report to the police. Turns out, that person was ravaged by Cole with the consequences including damage to his brain.

    Live-Action TV 
  • Used several times per season in 24, usually overlapping with You Have Outlived Your Usefulness.
    • In Season 1, Nina kills Teri because she overheard information that would have compromised her escape from CTU, though there are also other reasons considering both women's history with Jack.
    • In Season 2, Marie kills Reza just as he is about to clear his own name and find out who moved the funds for Syed Ali.
    • In Season 3, the reason why the Big Bad forces CTU to execute Ryan Chappelle.
    • In Season 7, the villains kill Dubaku after he is captured because he has information on them that he is using as blackmail to prevent being subject to You Have Failed Me and You Have Outlived Your Usefulness.
  • The 100:
    • Prior to the start of the series, Clarke's father was killed to keep him from revealing that the Ark's life support was failing and that the Council was planning to "cull" a large portion of the population to conserve oxygen. Clarke herself was put in solitary confinement for this same reason.
    • In the second season, Octavia figures out that Clarke and Lexa knew a missile was going to hit Tondc but chose to save themselves without warning anyone else to evacuate. Lexa tries to have Octavia killed to keep her silent, but Clarke stops her, insisting that Octavia is loyal to their cause and will keep their secret.
  • In the Agent Carter episode "The Lady in the Lake", Dirty Cop Det. Andrew Henry is murdered because he knows too much about Corrupt Corporate Executive Chadwick's dirty secrets, having covered up at least one murder for him.
  • Agents of S.H.I.E.L.D.: Variant. Robbie Reyes (AKA Ghost Rider) beats Daisy Johnson (AKA Quake) in a fight. Since he has the supernatural ability to know who deserves to die (and she doesn't deserve it), he lets her live. She shows up at his work the next day, making it clear she knows everything there is to know about him. They fight again, she gets knocked out, and she wakes up to find him going through her stuff. She knows too much about him to let her live, so he's looking for any sign that she does deserve to die, despite what his abilities say. In the end, he doesn't find anything, and they start working together pretty much because they're tired of fighting.
  • Andor: Luthen realizes that letting Cassian see his face and highly modified ship was a much greater risk than he intended when Cassian flees after the initial job instead of joining the rebelion. He orders him killed to prevent Luthen's cover from being blown but cannot track him down. The Empire is searching for him too in order to torture him into giving up Luthen, so this is a legitimate concern.
  • Arrow: This, combined with You Have Outlived Your Usefulness, is why Malcolm/Dark Archer kills the scientists who built the Markov earthquake-generating device for him upon its completion.
  • Parodied at the beginning of an episode of At Last the 1948 Show with Marty Feldman as gangster "Baby Face" Lip Salve and Graham Chapman as rival gangster "Diamond" Albert Nose Fetish. Baby Face demands to know when Prussia first acquired the hegemony of the North Germanic Confederation; 1866, says Diamond. Baby Face then asks for the angle of the plane of movement of the two outer and brighter of Uranus' satellites (Oberon and Titania) with the elliptic; 82 degrees, says Diamond. Finally, Baby Face asks for the square root of 7,974; 89.3, says Diamond. Baby Face says he now has to kill Diamond — he knows too much.
  • The Barrier: The plot involves the protagonists and other characters slowly uncovering the less moral plans and secrets of the dictatorship they live under, resulting in people getting killed because they have found out too much once in a while.
  • In Battlestar Galactica (2003), this is basically why Tory kills Cally, who has learned that Tory, Cally's own husband Galen, and Colonel Tigh are actually Cylons. Important to note that Galen is not in on this, and kills Tory for it when he finds out.
  • Parodied in The Black Adder. Edmund desperately tries to call off his plan to assassinate Dougal McAngus, who may have evidence proving his brother is an illegitimate child. When he tries to tell Percy that "He knows too much!" Percy, momentarily forgetting just why they are killing him (Dougal had stolen three titles from him), menacingly replies "That is why he must die!"
  • Blake's 7
    • In the pilot episode, a Double Agent betrays a rebel meeting to Federation soldiers who massacre them. Blake is the Sole Survivor but efforts to wipe his memory of the massacre prove unreliable. The agent insists that Blake be deposed of as he could expose his role. As Blake was once a popular Rebel Leader they decide to discredit rather than kill him, so Blake is framed as a child molester and deported to a penal planet. His legal defense team uncover proof that he's been framed, only to be murdered by the Federation agent.
    • In "Orbit", a fugitive Mad Scientist makes An Offer You Can't Refuse to the rebels. The offer can't be refused because; "Like you, I have a price on my head. So, having revealed my little sanctuary, I cannot allow you and your colleagues to leave. Not at any rate until we've reached an agreement."
    • Punned in "Moloch". Del Tarrant has his brain scanned (and all his memories and knowledge copied) by the eponymous Master Computer. Tarrant then quips that Moloch has to be destroyed because; "He knows too much about me."
  • Breaking Bad:
    • In Season 4, Hank discovers circumstantial evidence suggesting that Gus may be using Los Pollos Hermanos as a front for a massive drug-trafficking empire, and starts a one-man investigation to uncover it. Nobody else really believes him, but Walt and the audience know he's absolutely correct. Gus eventually gets fed up with how close Hank is repeatedly getting to his operations, and sets up a hit on him. Fortunately, Walt is able to prevent it from coming to pass, but at a serious cost.
    • In "Gliding Over It All", Walt arranges with Lydia and Jack to have all of Mike and Gus's former associates to be killed in prison to prevent any of them from being able to seek witness protection and testify against him now that Mike can't pay them to keep quiet (because he's dead). He also prepares to kill Lydia as a loose end, but Lydia sees this coming and keeps making herself useful to Walt so that he'll want to keep her around.
  • Buffy the Vampire Slayer:
  • In El Chapulín Colorado, the pirate captain Alma Negra always makes sure to kill whoever accompanies him to bury his treasure, to ensure only he himself knows where it is. El Chapulin is invoked precisely by the two unlucky saps who were handpicked for the job to escape their fate.
  • Cold Case
    • Part of the reason why the teacher in "True Calling" was murdered was that she had proof that another teacher was using drugs and forcing a student to bring them to him. When she called him out on it, he simply snapped and chased her to the streets before finally killing her.
    • The victim in "Blood On The Tracks", who wanted to confess to the cops about a crime he and several of his friends had been involved in that left another friend dead. With only one other person in the group agreeing with him, two of the others conspired to kill them both in order to ensure their silence.
    • This trope is the very reason the victim in "That Woman" was killed, when she accidentally learned the secrets of an Alpha Bitch, an Armored Closet Gay, and an accidental couple, even though she would have kept them anyway.
  • Daredevil (2015): In the pilot, this is why Fisk's goons are after Karen; she has a thumb drive with evidence of their criminal activity. Unusually, once the contents are disseminated, Fisk leaves her alone, as she doesn't know anything else that could further damage his operations.
  • Doctor Who:
    • "An Unearthly Child": This was the Doctor's justification for kidnapping Barbara and Ian. Couldn't have them revealing the existence of advanced aliens, after all.
    • "The Gunfighters": Johnny Ringo is in Tombstone looking for fellow Magnificent Bastard Doc Holliday, and the barkeep recognizes him, and threatens to go to the Earps.
    • "Boom Town": Blon Fel-Fotch Passameer-Day Slitheen, an evil alien disguised as the human Margaret Blaine, has been killing anyone who finds out that the nuclear power plant she, as Lord Mayor of Cardiff, is supporting is designed to deliberately melt down, as part of her plan to escape the Earth. She does spare one reporter who reminded her of her family, though.
    • "The Woman Who Fell to Earth": After the Doctor, Ryan, Yaz, Graham, and Grace encounter an electrical entity called a "data coil" on a train, they find they've been implanted with "DNA bombs" designed to kill them by scrambling their DNA. It's later revealed that the coil belongs to the antagonist of the episode, an alien warrior who's undertaking a ritual hunt in order to be named the leader of his species. However, the hunt is supposed to be a No-Gear Level, and he's using the coil to cheat, so he has good motive to attempt to kill anyone who finds out about the data coil.
    • "Arachnids in the UK": In a downplayed example, Najia Khan is fired from her job at a luxury hotel that's due to open soon after accidentally walking in on a sensitive conversation between the wealthy owner and his most trusted staff.
    • "The Witchfinders": Old Mother Twiston, the woman the Doctor and company see being drowned in a witch trial held by landowner Becka Savage. Becka is actually her granddaughter and killed her because Twiston, as the local healer, was the one Becka went to for help when she got possessed by "Satan" (a hostile alien lifeform), and she couldn't bring herself to amputate Becka's leg to get rid of it. Trying to save her own skin, Becka kills her by drowning so no one will know what she's trying to hide.
  • Dollhouse: Rather than being "terminated" (one way or another), a "handler" who has been exposed for raping his assigned "doll" is offered a task more suited to his evident personality: eliminate a woman who has inadvertently learned too much about the Dollhouse from an FBI agent investigating the organization. Only it's subverted when it's revealed that the target is a doll herself, one with a "killer" sleeper personality, and he's actually being sent to his death as part of a larger scheme.
  • An interesting variant occurs with John in Farscape because, while he knows that the Ancients put wormhole knowledge in his head, he isn't able to unlock that information himself for a few seasons. This leads to Scorpius chasing him across the universe and mind-probing him to figure out information that John is still trying to discover himself.
  • River Tam from Firefly. We don't find out what it is that she knows until The Movie Serenity (see Film), but we know her handlers paraded her in front of many top-level politics and military leaders... without realizing that she is a mind reader, so the government definitely considers it too much. So much so that two government agents killed an entire building full of people for the crime of having heard her speak gibberish while she was under arrest.
  • Flashpoint: The episode "Jumping At Shadows" has three hitmen trying to track down and kill a little girl who saw them murder her best friend's family. The crime the girl witnessed was also a case of this; the family was killed because the father, an accountant, uncovered evidence of a crime in the course of his job and was planning to testify.
  • Forever:
    • Henry decides this of the mysterious caller. His plan for silencing the caller, in an interesting subversion of the trope, is simply to move far away and outlive the person. Of course, as he finds out at the end of the first episode, the other person is also immortal, so outliving him isn't an option.
    • In the flashback of "New York Kids" Henry comes across a bookie (or their enforcer) shooting a client who couldn't pay his debts. Henry identifies himself as a doctor and tries to help the victim, but the shooter points out Henry is now a witness, and shoots him as well.
  • Game of Thrones:
    • The series kicks off with the Starks receiving a letter stating that Jon Arryn was murdered which they decide was due to this trope.
    • Bran is defenestrated for seeing too much, even if he doesn't completely understand what he saw: the queen having sex with her twin brother.
    • Dontos Hollard receives a crossbow bolt because he cannot be trusted with a secret.
  • There's this exchange at a hearing in Get Smart:
    Senator: Mr. Smart, how many arrests did Control make last year?
    Maxwell Smart: I don't know.
    Senator: Who's the number one man in your organization?
    Maxwell Smart: I don't know.
    Senator: How many cases were assigned to Control last year?
    Maxwell Smart: I don't know.
    Senator: What would you do if you were fired, Mr. Smart?
    Maxwell Smart: They can't fire me.
    Senator: And why not?
    Maxwell Smart: I know too much.
  • This is the driving element of the pilot of Graceland. Felix is a low-level drug dealer who is caught by the FBI when he tries to trade a truckload of counterfeit jeans for a duffel bag full of cocaine. His Russian bosses are not happy about this since Felix knows too much about their operations and could talk to the feds to avoid a lengthy prison sentence. They kidnap Felix's family so he stays quiet but Felix realizes that they will have him killed in prison and then murder his family so there are no witnesses. He cooperates with the FBI and Mike is sent in undercover as Felix's brother-in-law. The Russians like to invert the trope by having someone commit a murder for them and then they blackmail the person with the threat of turning them in to the police. Mike offers to kill whoever the Russians pick since this will give them enough leverage over Felix to ensure that Felix never talks and they have no need to keep his family hostage. The target turns out to be another witness who knows too much and it quickly becomes clear that the Russians will not keep their side of the bargain and will instead kill everyone who knows about the plan.
  • Homicide: Life on the Street: Sam Thorne is killed by a Columbian drug cartel when he digs too deep into their operations in Baltimore.
  • House of Cards (US):
    • One of the most shocking moments of the Season 2 premiere is when Frank Underwood pushes Zoe Barnes in front of a subway train, in order to silence her about their backchannel communications, which he's been using to manipulate events in his favor.
    • "Chapter 64", the penultimate episode of Season 5, sees two examples of this, one lethal and one not. Frank pushes Secretary Durant down the stairs, hospitalizing her, so that later she can't testify at a Congressional hearing about his dirty dealings. Later, Claire kills Tom Yates via poisoning to stop him from publishing a manuscript detailing everything she and her husband have done to stay in power (including the murders of Zoe and Peter Russo).
  • Intergalactic: Once Rebecca has coerced Wendell into giving up information on ARC by threatening his son, she tells him to run back to him... only to order him shot for escaping, since she's keeping this for herself, so no one else can know about it.
  • El internado: Las Cumbres:
    • Elías announces to Mara that they intend to see her in prison for her actions but thanks to a good shove off a cliff, does not live to make good on that announcement.
    • León forces Darío to hand over his watch containing data. In turn Darío lies to grief-stricken Celia, making her think León murdered her daughter Alba. Celia ends up shooting León and Darío recovers his watch.
  • In the JAG episode "Someone to Watch over Annie", the 10-year-old son of Harm's Romantic False Lead by accident gets to see a murder at Andrews Air Force Base while slipping away from his school class when on a tour. It turns out the bad guys are weapons smugglers who don't shy away from trying to kill witnesses.
  • In Jupiter's Legacy, Walter kills Raikou because she discovered his plans to create instability within the Union that would make him the leader and help him with his plans of ruling the country.
  • Kamen Rider Build: Prior to the event of the series, Takumi Katsuragi finds out about the true identity of Blood Stalk and plans to kill Stalk, so Blood Stalk sabotages said plan and remove his memories, turning him into our amnesiac protagonist Sento Kiryu.
  • The Killing: The reason the Pied Piper targets and kills Bullet in Season 3; she had called the police saying she had info on his identity.
  • As revealed in the docuseries Menudo: Forever Young, Bolivar Arellano, a photojournalist who worked around the group saw many things that he found disturbing (the members working long hours, an inappropriate environment). Just when he was going to appear in the popular "Carmen Jovet Controversial" talk show, several attorneys showed up with an injunction to prevent him from making his allegations public. He later faced a lawsuit for defamation and was found guilty.
  • Rare (anti?)heroic example in Merlin in the series 4 finale. Merlin knows that Agravaine cannot be allowed to reveal to Morgana that he's Emrys, and so kills him off. Alright, he waited until the guy pulled a knife to actually do it, but it's heavily implied that he wasn't going to leave alive either way.
  • Million Yen Women: Two of the women figure out who invited them to stay at Shin's house over the course of the story and get killed as a result.
  • In the Mission: Impossible episode "The Town", Phelps stumbles across a town of Russian spies and discovers the fact. They intend to make his death look like natural causes. Fortunately, he has four brilliant colleagues.
  • NCIS: The episode "Witness" was based on this motive. It included a medium Tear Jerker, as McGee narrowly failed to save the girl, who he'd hit it off with just the day before.
    • In the episode "Democracy", five people who had evidence of a voting fraud conspiracy "accidentally" die before they can reveal the fraud. Unfortunately for the conspiracy, one of them managed to get the list of their names to Charlie shortly before being killed, who determines that the odds of five random people dying in a given two-week period are approximately a bajillion to one. Don orders a second autopsy on the one who gave Charlie the list, which confirms that she was murdered, and the attempt to tie up a few loose ends has now attracted the attention of the Federal Bureau of Investigation.
    • In "Disturbed", the episode after the credits opens with a murdered mailman who was last seen alive outside of a home where a woman was killed. He waves at the repairman entering the house. The repairman is a serial killer and he kills both his intended victim in the house and the mailman who could place him there. Nearly an aversion, since the mailman only possibly knew something.
      • The killer is stated to do this to pretty much anyone who comes even remotely close to being able to identify him. Unfortunately for him, one of his early attempts at this wasn't quite successful, and that witness ends up becoming the key to taking the killer down.
  • Person of Interest: Northern Lights, the organization in charge of the Machine, has a habit of killing anyone who finds out even the smallest details about it. When Sameen Shaw, one of their own operatives who is sent on extremely important missions by the Machine, asks one too many questions, her boss orders her and her partner killed. Shaw hunts him down and lampshades that this was completely unnecessary. They had been following orders when they thought people were being tortured for information; the truth is actually less horrifying (a benevolent AI studies surveillance and tracks terrorists before they can strike). She kills her boss in revenge but pointedly leaves everyone else alive because she knows the work is important.
  • Someone from Pretty Little Liars is in great danger in the Summer Finale of the show. A even sends a text to Emily which says 'She knew too much.'
  • In Prison Break, Alexander Mahone is tasked by the FBI to apprehend the Fox River 8 but is really trying to kill them at the behest of The Company. Scofield and Burrows need to die because they're trying to expose their conspiracy and the remaining six on the off chance that they've picked up any compromising information.
  • The Shadow Line:
    • This is why Jonah Gabriel and his partner were shot before the events of the series, in that they came too close to discovering the true extent of police involvement in Counterpoint.
    • Ross McGovern is killed for investigating the above incident too closely because his investigations could have led to what Gabriel and Delaney discovered.
    • Even invoked in episode 6, when Glickman tells Gabriel to confront Commander Penney with the news that he knows about Counterpoint. They're counting on Penney then sending Gatehouse after Gabriel, because they want to lure Gatehouse into a trap.
  • Star Trek
    • Star Trek: The Original Series: In "The Conscience of the King", it's revealed that nine people were able to visually identify Kodos the Executioner, who was responsible for the massacre on Tarsus IV. Early in the episode, one of them is found dead, and it turns out that he's the seventh witness to bite the dust. In addition, Captain Kirk and Lieutenant Riley were also witnesses, and they're also targeted for assassination.
    • Star Trek: The Next Generation: In the episode "Reunion" Duras kills K'Ehleyr after realizing she knows the truth of what happened at Khitomer. It doesn't end well for him as he dies not long afterwards at the end of Worf's bat'leth.
    • Exploited in the Star Trek: Deep Space Nine episode "In The Pale Moonlight". After the Romulan senator figures out that the data rod Captain Sisko gave him is a fake, he heads home to the Romulan empire when his shuttle suddenly explodes because Garak put a bomb on it. As Garak explains it, the Romulans will find the shuttle and assume that the Dominion murdered the senator to try and keep him from informing the Empire about the Dominion's plans and the irregularities in the data rod are a result of the explosion.
  • The Tomorrow People (2013):
    Dr. Culix: The boy on the bike? He's seen too much. Get him!
  • UFO (1970): A continuing duty of SHADO (Supreme Headquarters Alien Defence Organisation) is to suppress information on UFO incidents to prevent worldwide panic over the knowledge that beings from another world are harvesting human organs. Their methods include intimidation (ranging from beatings to government pressure on the employers of the witness), conscription into SHADO, amnesia pills, and even murder.
  • In A Very English Scandal, politician Jeremy Thorpe allegedly tries to have Norman Josiffe murdered because he and Norman were once lovers (at a time when such an affair would be even more damning and career-ending) and Norman refuses to be intimidated or bought out.
  • Warehouse 13:
    • Implied in Claudia's first episode after she breaks into the Warehouse to coerce Artie to help her save her brother (as in, she knows about the Warehouse and now we have to do something about it). They seem like the kind of folks who consider death to be a (albeit viable) last resort, though, and Claudia ends up joining the team.
    • Something very similar happens in the first episode of Season 3 — the warehouse agents run into ATF agent Steve Jinks on a mission, and their attempts to explain the situation away don't work because he's a Living Lie Detector. Since he's in on the secret and already a federal agent, he gets recruited.
  • Several (main and minor) characters on The Wire have been killed off because of this trope. Whether they do or don't know too much, the results tend to be tragic.
    Stringer Bell: "But there go a life that had to be snatched, Avon (...) Twenty years above his fucking head. He'd flip, man! They got you, me, and Brianna! No fucking way, man! Hell, no! Now, I know you family, you loved that nigga, but you wanna talk that 'Blood is thicker than water' bullshit, you take that shit somewhere else, nigga! That motherfucker would've taken down the whole fucking show, starting with you, killer!"
  • In The X-Files, Mulder knows entirely too much right from the start and then gathers more information along the way. When attempts to get him to come to the dark side fail, the Syndicate try to destroy him instead. Since Mulder is more valuable to them alive than dead, they tend to do terrible things to people he cares about. Arguably the worst was giving Scully an inoperable tumor that spelled a slow and painful death for a season (until a cure is found by Mulder's snooping ways, of course).

  • In Goddess Creation System the king passes away officially from wounds sustained in a tiger attack some months before but probably really from poison. To cover this up temporarily so they can keep things stable, the queen and her brother have the imperial doctor poisoned so he can't tell anyone.

  • "Jane Doe" by Within Temptation. The titular character is killed for knowing some secret of the person the song is being addressed to:
    She had to go or they would know,
    all you tried to hide.

    Tabletop Games 
  • Massacards: The Killer’s motivation to find out The Witness’s identity is because they know who the former is.
  • Warhammer 40,000: This is a possible outcome for planets assaulted by the forces of Chaos. Even if they manage to defeat Chaos, The Holy Orders of the Emperor's Inquisition may decide that it would be best if they couldn't tell anyone about it, since the true nature of Chaos is supposed to be kept secret from the general public.


    Urban Legends 
  • The Home Guard Auxilary Units were stay-behind units trained in the event of a German invasion of Britain during World War II. Each patrol consisted of local men recommended by their Chief Constable. They had secret orders only to be opened in the event of an invasion. One man opened his anyway and found to his shock that his first mission was to assassinate the Chief Constable, as he was the only man who knew the identity of the unit members.

    Video Games 
  • Ace Combat:
    • Ace Combat 3: Electrosphere:
      • In a Flashback, its revealed that Rena Hiorse was the test pilot for General Resource’s Night Raven project. However, when Rena was interviewed at the age of nine, she inadvertently revealed its existence to the public, which led to General Resource to terminate anyone who was involved in the project. This included Yoko Martha Inoue, whose death led to Abyssal Dision to vow revenge against the world for taking Yoko from him.
      • In the Omega Ending, this is one possible reason for why Simon Orestes Cohen purged Nemo in the simulation once all possibilities were run through the program, as he couldn’t risk the possibility of Nemo alerting the UPEO, General Resource, Neucom, or even Dision of his treachery. However, Simon then turns right around and releases a copy of Nemo into the real world, with the intent to engineer events so the Inter-Corporate War occurs in reality. As it turns out, he too was close to Yoko, and blamed Dision for her death; the entire purpose of the Inter-Corporate War simulation was to ensure that no matter the outcome, Nemo would kill Dision. For the plan to work, however, Nemo had to function on its own, without knowledge of how the Inter-Corporate War would come to pass, so the copy released by Cohen was a clean one.
    • Two-thirds of the way through Ace Combat 5: The Unsung War, the Wardog Squadron discovers that the war between Osea and Yuktobonia was instigated by an organization called the Grey Men, to avenge their homeland of Belka, after the Grey Men try and fail to wipe them out while returning from a mission. As a result, the Grey Men resort to Plan B: Frame Wardog as traitors and get them executed by their own countrymen. While they succeed in getting the Wardog Squadron branded as traitors, they fail to get them eliminated, and the Wardog Squadron goes on to stop the Grey Men from escalating the war any further.
    • Ace Combat 7: Skies Unknown: In the mission Faceless Soldier, Full Band brags to AWACS Bandog that he’s acquired classified information that he intends to reveal once the mission is over. When the Spare Squadron is ambushed by AI-controlled aircraft using spoofed Osean IFFs, Tabloid suggests that they form an element on Trigger, and for Bandog to register anyone not in the formation as an enemy. When they do, Bandog asks for Full Band’s location, and flags him as an enemy, resulting in him getting shot down and killed by Count. When the squadron calls Bandog out on it, Bandog insists that it was an accident.
  • The protagonist in Arcanum: Of Steamworks & Magick Obscura is an example of the second type: all he knows is a gnome gave him a ring and told him to "Find the boy", but due to the conspiracy's repeated attempts to murder you, you eventually figure out their incredibly convoluted plans.
  • BioShock:
    • One of the Audio Diaries in the first BioShock records this just as it happens. Diane McClintock's last diary has her accidentally walk in on "Atlas" as he's recording a message in his real voice. He hastily puts on his Irish accent and asks her to come closer. In the game, you find her corpse on his desk.
    • BioShock 2 has a rather extreme case in Stanley Poole, who decided that the whole of Dionysus Park knew too much regarding his hedonistic mishandling of funds, so he flooded the park, killing everyone there. He also sent Eleanor Lamb, who learned about both the overspending and him being there to spy off on her mother Sofia, to be converted into a Little Sister. This all turns out to be wholly unnecessary, as Sophia knew what Poole did the whole time and was just toying with him.
  • Call of Duty: Modern Warfare 2: After sending all of the Task Force 141 to both of Makarov's safehouses, General Shepherd betrays them all because he suspected that they knew about his plans to make the U.S. the most powerful country in the world.note 
  • BlazBlue: Continuum Shift: This, coupled with Protectorate issues, turns out to be the big motivation behind Captain Hazama's attempt on the life of Makoto Nanaya in Jin's story. Makoto turns out to be big friends with Noel Vermillion and Tsubaki Yayoi, both of whom had big roles to play in Hazama's plan, so getting her as far away from them (like, say, Ikaruga) is high on his priority list. Unfortunately for him, she winds up finding out that Noel Vermillion is a Murakumo unit, an artificially created being with the purpose of using the Eye of the Azure to destroy the Master Unit. As if that wasn't enough, she winds up falling into an alternate timeline where Noel didn't exist and Tsubaki wound up dead, which ironically is fuel Hazama used to facilitate Tsubaki's Face–Heel Turn, and the first thing she does is block an attempt on Jin's life by Hazama. The knowledge of Murakumo Noel is dangerous enough, but the possibility that the events Makoto witnessed could abort or reverse Tsubaki's change in alignment mean that, to him, it's not worth chancing her staying alive.
  • In Command & Conquer: Red Alert 3, Premier Cherdenko tells the Commander this to his face right before killing him because he has outlived his usefulness. In this case, the "too much" is that the Soviet Union was on the brink of losing before Cherdenko used Time Travel to Make Wrong What Once Went Right and, in the process, made himself Premier. In earlier missions, he already killed two of the other people who knew, his right-hand man General Krukov and the time machine's inventor, Dr. Zelinsky.
  • In the flash game The Dead Case, it's revealed that when she was alive, the church ghost had unknowingly been married to a serial killer. When she found evidence for what he had been doing, he burned down the house and killed her.
  • Deadly Premonition gives this as a reason why Becky Ames gets killed. Said character was there when Anna Graham was killed and her murderer also knows that they have an item that could be a good hint for his identity. Diane Ames gets killed for similar reasons, after the previous character gave them more knowledge.
  • Elohim Eternal: The Babel Code: In the Fortress of Dan, Henock kills and imprisons anyone who enters, since the aggelia recordings there reveal that Nestor killed Attika for trying to form a truce with the Cainites. This kind of knowledge could jeopardize the Forever War that Henock's masters, the Kosmokraters, wish to maintain.
  • Etrian Odyssey: After the 4th Stratum, the player's guild discovers that what appears to be a medieval society is actually built on top of the ruins of Tokyo. Visil sends Ren and Tlachtga to kill them in order to avoid ruining the mysteries of the Yggdrasil Labyrinth. When that doesn't work and the party adventures deeper, they confront Visil, who explains that Yggdrasil was built to reverse the environmental damage brought about by humanity and that he is the last surviving scientist who worked on the Yggdrasil Project at least 1,000 years ago. With that out of the way, they try to kill the party to protect that ultimate secret.
  • In Fallout: New Vegas, if you convince Veronica to leave the Brotherhood of Steel for the Followers of the Apocalypse in her personal quest, several fanatical Paladins will massacre a Followers outpost and then try to go after Veronica since they see her as a heretic who might end up spreading knowledge about the Brotherhood that they're devoted to keeping secret. After fighting them off, Veronica is left horrendously traumatized, but she's sure that she made the right choice in leaving the Brotherhood.
  • Fire Emblem:
    • Takes place twice in Fire Emblem: The Sacred Stones: Some characters know well what the Hell is going on in the Empire of Grado (the Cleric Natasha whose mentor, a well-respected high priest, was killed for discovering that the Emperor was dead and revived as an Artificial Human and the Shaman Knoll, Lyon's second-hand in the project to revive said Emperor). The Empire frames both of them as traitors; Natasha has to flee from her homeland and Knoll is imprisoned and slated for execution... but in-game, both survive and join Eirika's (in Natasha's case) or Ephraim's (in Knoll's) troupes.
    • Towards the end of the Conquest route in Fire Emblem Fates, the Smug Snake Iago figures out that the Avatar is a traitor when his men discover a certain someone who was meant to be killed. After hearing his accusations, the Nohrian royal siblings decide that it would be better to kill Iago and Hans to protect their foster sibling's life rather than face the wrath of an enraged Garon. Iago and Hans really don't help their case by directly attacking the Avatar in front of the Nohrian siblings, too.
    • Fire Emblem: Genealogy of the Holy War: Arvis kills Sigurd and his companions in part because they know who Deirdre is, meaning that he will not be able to rely on her Easy Amnesia concealing her identity.
  • One of the scenarios in Frostpunk has you deal with evacuating the inhabitants of your doomed city with a shuttle to a transport (that is not big enough for everyone) in order to go somewhere else. Unfortunately, you as leader don't know of any other place to go, but you can choose to lie about it and claim you know of another city in order to prevent people from losing heart and working less efficiently for the rest of the scenario. If you lie however, nothing happens at first, but soon one citizen will figure it out and confront you, threatening to expose you unless he and his family is given priority in the evacuation. You can agree to his demands, refuse or have him killed (since He Knows Too Much). If you give in, he will leave and not expose you, but this leads to four more citizens confronting you about the same thing, and this time the options are only to kill them as well or to allow them to tell the truth. If you allow the truth to come out or refuse the blackmail, a riot will break out. This leads either to you having to suppress it by force, injuring or killing dozens of citizens, or to a great number of people leaving for the transport on foot instead of via the shuttle meaning most of them will die on the way there, and to the remaining citizens despairing to a point where you are likely to get an uprising on your hands, which leads to a Game Over. Maybe you should just have accepted that slight efficiency loss from the start...
  • In Ghost Trick, this was the reason that Sith arranged for the deaths of Jowd, Cabanela, Pigeon Man, and Lynne. All of them had some interaction with/knowledge of the Temsik meteor, and he wanted to be the only one to know about its existence. Because those were the same people that Yomiel, the owner of the last shard of the meteor, wanted dead, this worked out fine... until Yomiel realized that he himself fell under this trope, and Sith was preparing accordingly.
  • Downplayed at the beginning of Golden Sun. In the aftermath of the boulder incident, young Isaac and Garet overhear Saturos and Menardi talking about how they caused said incident. When they are caught eavesdropping, they are lucky enough to get off with a No-Holds-Barred Beatdown that wipes their memories of them.
  • In Half-Life, after the Black Mesa research facility triggers an Alien Invasion, the Hazardous Environment Combat Unit are sent in to combat the aliens and kill all the scientists and security guards. Later on, Black Ops is sent in to kill the HECU survivors. Finally, the G-Man nukes the entire base at the end. As Freeman's Mind puts it:
    Freeman: So option one is this is a cover-up, and the troops are being covered up, too. Like one out of every five troops is secretly a merc, and his job is to kill the other troops. Then they'll the bomb the place to kill the mercs, then they'll kill the bomber pilot, and then write this all up as a... plane accident. Why not?
  • In Halo 3: ODST, an NMPD officer on Kinsler's payroll is instructed to make sure Dr. Endesha is dead, and to eliminate any witnesses. Unfortunately for him, you are a witness. Let's see: a corrupt cop versus an elite UNSC shock trooper. Guess who wins...
  • In the Hitman series, this is pretty much the only reason 47 will kill an innocent (in canon), as his existence is already very volatile and he cannot afford to let anyone (other than a select few) know about him.
  • Hotline Miami 2: Wrong Number: After Jake figures out 50 Blessings plan all on his own, if he survives his raid on the Russian Mafia’s meth lab, the Manager kills him by taking him to a safe house and shooting him in the head. This is not how Jake canonically dies, however — as his corpse was shown in the previous game, his canonical death came when the Russian Mafia stopped his attack, captured him, and killed him after he refused to give any information.
  • Kindergarten:
    • It's possible for the player and Lily to be killed after stumbling upon something you really shouldn't see.
    • This is the reason behind Billy's disappearance — he walked in on the janitor disposing of a monster corpse, and was subsequently chosen to be the headmaster's first human guinea pig.
  • L.A. Noire: Dirty Cop Roy Earle sells out By-the-Book Cop Cole Phelps by revealing his affair with Elsa Litchmann as he knows that if he keeps on moving the ranks, the Suburban Redevelopment Fund and its conspiracy will be exposed. However, it only encourages Cole to investigate Elysian Fields, much to Roy's dismay.
  • Life Is Strange: At one point, Max has the opportunity to warn Victoria that Nathan is dangerous and has murdered at least one person. If Victoria believes her, she runs off to ask her favorite teacher, Mark Jefferson, for help. Except Jefferson has been playing Nathan like a fiddle and is the one who actually committed the murder. He kills Victoria without a second thought.
  • LunarLux: Anyone who tries to work with Saros to be spared from his Murk experiments gets betrayed anyways, since he doesn't want to risk any loose ends. The only reason he doesn't immediately kill Nickle the Murk Slayer is because he wants to find the latter's anticore stash first. Once Bella and Nickle reveal the truth of the Murks to the Lunex Space Station, Saros hacks into the space station and tries to crash it into Luna's astro barrier.
  • In Mass Effect, on Noveria the volus, Han Olar, asks an asari commando about to kill him if he'll get a "you know too much speech?" Fortunately, Shepard saves Olar before the commando can kill him.
  • Max Payne:
    • In the first Max Payne, it turns out that the junkies who killed the title character's wife and baby girl were sent by Nicole Horne after a dossier about Horne's project found its way to the wife's desk and Horne decided to silence her by "any means necessary." Tragically, Max's wife was trying to tell him about this ("a strange memo, something about Vikings"), but he ignored it.
    • In Max Payne 3, Da Silva knows this will happen to him if he digs too deep, so he points the much more combat-competent Max in the right direction instead.
  • In Metal Gear Solid, ArmsTech president Kenneth Baker is targeted by the FOXDIE virus alongside the members of FOXHOUND in order for the Pentagon to silence everyone involved with the Metal Gear project and recover the data for it. He was fully aware of what had been done to him and attempts to warn Snake that he's being used, but dies before he can finish.
  • At the end of Misao, if you choose to sacrifice the wrong person, you end up being transported back with Sohta — the killer. He concludes that Aki knows too much and promptly does away with her. Truth also reveals that this is why Ayaka was killed.
  • Murder in the Alps:
    • In Deadly Snowstorm, all the five murders the Nazi spy Claudia Perret commits are basically a series of increasingly ill-thought-out efforts to draw attention from herself. Professor Kinsky catches her rummaging through his luggage and threatens to tell this to the police and all the hotel guests, so she stages a heart attack to off him. Ulla Lund discovers on Kinsky's neck the puncture mark left by Claudia's syringe and intends to tell this to Dr. Hartmann, so Claudia stages another heart attack. When Dr. Hartmann intends to show Anna Myers and Walter McCain something, Claudia rushes to shoot him without knowing that his discoverynote  has nothing to do with the murders. Claudia's employer, Mr. Petersen, grows suspicious of his nurse and keeps demanding straight answers from Claudia until she gets rid of him. And finally, when Giovanni Rossi is believed to be the murderer and tied up, only Walter remains suspicious of Claudia, so she kills him as well.
    • In The Heir, the murderer grows worried about the protagonist Anna Myers' investigation that's more thorough than that of the local police chief, so they try to kill her by dropping a large rock on her. Vincent Freeman figures out that Osvald Bernstein is the murderer and tries to extort money from him in exchange for his silence. Osvald comes to meet Vincent as requested, but he buys the latter's silence with a knife stab instead of money.
    • The climax of Ladies of the Night reveals that Petrus Krämer was captured and beaten up at Oskar Havel's hideout by the latter's accomplishes, and since the prostitute Susi Wiget was there at the time, they shot her.
  • In NieR: Automata, the Android forces employ Scanner-model units as intelligence agents and combat hackers in their war against the alien-built Machines. Unfortunately, Scanners have a natural curiosity, and their abilities let them uncover sensitive information that YoRHa Command would rather keep secret. Enter the Executioner-model androids, who are designed to destroy rogue Android units, and are routinely paired with Scanners to serve as minders in case they ever learn too much. Protagonist 2B is revealed late in the game to actually be designated 2E, and has been ordered to execute Deuteragonist 9S several times before the game's events, which torments her since she's fallen In Love with the Mark. And even though 9S' memory gets reset to a data back-up each time he "dies", he's figured out that his partner has been killing him, yet keeps developing feelings for her.
  • Nine Hours, Nine Persons, Nine Doors: Ace's motivation for killing Clover, Snake, Musashidou, Nijisaki, and the Ninth Man are them knowing about his own past. Though, it was also to obtain his '9' bracelet which would put him at an advantage.
  • Nintendo Wars: Hawke and Lash from Advance Wars: Dual Strike are attacked when Hawke figures out the Big Bad's true motive for starting a war. Of course, the allied nations save them and they all fight the Big Bad together. Hm. Maybe the Big Bad was planning on getting rid of Hawke and Lash anyways since Lash is caught up in Hawke's problem for almost no reason.note 
  • Before the Rank 8 fight in No More Heroes, Travis interrupts Shinobu's presentation before her class. She sighs, tells him to meet her outside, then draws her katana as he leaves. When they meet up, she's complaining about how hard it is to lead two lives... at which point Travis makes the connection: "You killed them, didn't you?"
  • Octopath Traveler:
    • The Crow Men killed Primrose's father because he was looking into things he shouldn't have.
    • Gideon tries to kill Cyrus for discovering his laboratory under Quarrycrest where he conducts Blood Magic experiments on innocent townspeople.
    • Yvon threatens this upon Therese and Cyrus for butting into his affairs.
  • Octopath Traveler II:
    • Crick is killed by Captain Kaldena for investigating too far in Vados' murder, which leads to some forbidden books about the Moonshade Order, the source of power Kaldena is looking for.
    • Clarissa's husband Ethan was killed by Stenvar's men (who made it look like a suicide) because he correctly suspected that Osvald was innocent of the crime he'd been accused of.
  • In Oddworld: Stranger's Wrath, after being captured and revealed to be a Steef, Stranger immediately proceeds to kill D. Caste Raider and his gang, using only his bare hands. The Achievent for this is even named "He Knows Too Much".
  • This happens to Kyle in Parasite Eve 2. The President is outraged that Kyle suddenly resigned as a mole without going through the proper channels and is also worried that their spy might leak info.
  • Prayer of the Faithless: Mia, Amalie, Serra, and Reyson end up making a major enemy because they learned something they shouldn't have. They discover Commandant Vanessa's lab in Lavingard, Vanessa orders Amalie to kill everyone else, since this knowledge could throw Asala into chaos. When Amalie loses, Vanessa decides to falsely label the four of them and the Honneleth refugees as undead Stranded so that all of human civilization will try to kill them on sight.
  • In [PROTOTYPE], this trope ends up being the cause of the whole plot. After the real Alex Mercer was hired to make a virus ten times deadlier, his employers who were under investigation, decided to permanently silence all loose ends. Just as their assassins caught up with him, the real Mercer spitefully unleashed the virus to take the whole world with him just before he was gunned down.
  • In Puyo Puyo Fever, Raffine reaches Ta-Toon-Da Castle faster than Accord expected and learns the whole search for Accord's supposedly missing flying cane was staged. After defeating Accord's cat puppet Popoi, Raffine is "awarded" with an amnesia-inducing hit to the head with a mallet and is ordered by Accord to "forget what you saw today".
  • Resident Evil:
    • According to the backstory, George Trevor, the architect who helped design the mansion in the first Resident Evil, didn't realize that Ozwell Spencer (the founder of Umbrella) grew paranoid about him. Because George helped build a mansion that was filled with traps and secret rooms, he knew everything about the place. Ergo, Spencer wanted him dead so that the secrets would never get out. George tried to escape the mansion grounds, only to fall into a pit, which had a gravestone with his name on it, and died due to thirst and starvation.
    • One of the diary entries in Resident Evil 2 is written by a secretary who got chewed out by Chief Irons for bumping into his statue. Later on, they discover a hidden torture dungeon Irons has underneath his office. The last page of the diary is left blank, implying that the Chief found out and permanently silenced them.
    • Resident Evil 2 (Remake) incorporates this into Mr. X's appearance and Umbrella's motivations. Anyone who knows about Umbrella's hand in the outbreak (i.e., any non-zombie not working for Umbrella) is a threat. The solution? Send in the nigh-unkillable Mr. X to silence anyone who knows something... permanently.
    • The titular Nemesis in Resident Evil 3: Nemesis is a Tyrant bioweapon specifically created to hunt down and kill the surviving S.T.A.R.S. members that bore witness to Umbrella's dirty secrets from the first game. Nemesis kills Brad and chases Jill throughout the whole city until she manages to kill it at their final encounter. One of the unlockable epilogues reveal that the U.S. government detained Leon and Sherry since they witnessed the Raccoon City Incident and both knew too much. In exchange for keeping Sherry safe, Leon agrees to become a government agent to help fight bioterrorism. Sherry herself would be subjected to medical exams and experiments for several years due to the now dormant G-Virus in her body.
    • All of the Survivors from Resident Evil Resistance, save for one, found themselves thrust into Umbrella's barbaric experiments after uncovering something they shouldn't have: January was close to uncovering Umbrella's dealings with the Raccoon City police, Valerie was an Umbrella intern who asked ont too many questions about a colleague's mental disorder, Becca had a run-in with zombie dogs, Tyrone fought fires at an Umbrella facility with nasty secrets, Martin stumbled on damning documents while doing maintenance at an Umbrella-run hospital, and as estabilished above, Jill was a witness to the goings-on at Arklay Mansion. The one outlier is Samuel, who volunteered for Umbrella's medical trials.
  • Return Of The Obra Dinn:
    • Thomas Lanke eavesdrops on one of the crew members suggesting mutiny to another, before they notice him. He immediately panics, yelling "Mutiny!" at the top of his lungs. By the time the other crew members get there to help, he's already been fatally stabbed by said mutineer.
    • Earlier, Nunzio Pasqua has the misfortune of going to the cargo hold just as Second Mate Nichols is attempting to steal the Formosan chest. He also receives a fatal knife wound.
  • This sets up the plot of Robinson's Requiem: you and several other Robinsons have discovered that AWE banishes or kills any agents who have potentially contracted alien diseases or virii while exploring unknown planets. Unfortunately for you, AWE finds out that you've learned this Awful Truth and decides to send all of you to the Death World Zarathustra.
  • The Secret World:
    • This is a regular occurrence: when you finally discover The Secret World, you're either in or you're dead. Between the traditional demon-purging Templars, the control freak Illuminati, the mayhem-inducing Dragon, and the mercenary (and non-playable) Phoenicians, you're usually dead by dawn if you run. And these are the GOOD GUYS. Most of the bad guys just leave victims and corpses for you to find. The neutral factions are too bogged in their own problems to deal with any of this. The recruiter for the Templars outright says that now that your player character knows that the supernatural is real through their own superpowers, they're a target for anima harvesters. You either get syndicated or you go on the hunt-or-be-hunted for the rest of your life. Considering that there are no levels in the game and respawn points require a sponsor, that would mean you're finished if you choose the latter.
    • In one mission, two nobodies are chased halfway around the world and declared public-enemy heretics because they have tiny, tiny snippets of information against a super-cult. One of them is suicidal (and has been since she was 14), the other doesn't even know the password to the tablet PC he stole, or what is on it. It's you. No, seriously. You get to see some of your character's extra stats. For example, greatest fear? Your handler.
      Mihail: Hey, it could be a recipe for lemon pie, for all I know.
  • In Sly 2: Band of Thieves, Carmelita is incriminated after being accused of turning against Interpol, only since The Contessa realized Carmelita would've eventually discovered The Contessa was a member of the Klaww Gang.
  • In Sonny, this is the reason the ZPCI board the White November in the first game and destroy the village in the second game. In the former, Sonny kills the soldiers after they take out Louis, escaping on a lifeboat after receiving the MacGuffin. In the latter, Sonny and his crew fight the leader of the troops briefly before fleeing on an old train.
  • In Splinter Cell: Conviction, while Sam is interrogating Galliard, a man working for a mysterious group named Megiddo, he learns about Megiddo controlling multiple locations, but before he has a chance to obtain more information, Galliard is assassinated by a shooter to protect Megiddo's identity. The shooter responsible for assassinating him later dies in a car bomb explosion, assumed to be arranged by Megiddo, so the shooter can't reveal Megiddo's identity, if he is ever caught by Fisher.
  • Transistor: Henter Jallaford had a reputation of never stopping his investigation once he got curious. Then he saw something in Cloudbank, as the Camerata knew he would, then they ambushed him to deal with him immediately.
  • The Walking Dead (Telltale):
    • Episode 1: This is a good reason to not choose Carley to live, especially if playing Lee as a paranoid jerkass.
    • Episode 2: Larry falls into a weird inversion of the trope, as he threatens to tell everyone and he's being an antagonistic jerkass, while you may play Lee as a man of a gentle spirit.
  • Warframe: In the backstory, a Dax Super-Soldier discovered that Ballas, one of the highest-ranking people in the Orokin Empire, was planning to sell out the entire human race to the Sentients. Ballas decided to silence him, but instead of just killing him, he infested him with a carefully controlled version of the Technocyte Plague, turning him into one of the first warframes, driving him violently insane, and enslaving him to Ballas' will. And then he made the Dax kill his own son.
  • In Yakuza: Like a Dragon, the Ijin Three agree that Nanba cannot be allowed to live because he might expose their money counterfeiting scheme, with Zhao calling hitmen to take him out. However, he calls them off after the Geomijul burn down the counterfeiting operation to save themselves.
  • In Yandere Simulator, if a student witnesses you committing murdernote , but you manage to get away with it, they will constantly talk about it to other students, which will constantly dip your reputation. The solution? Leave No Witnesses.

    Visual Novels 
  • This happens a lot in the Ace Attorney series.
    • In the first game, Mia was murdered because she had pieced together Redd White's blackmailing schemes.
    • Justice for All:
      • The first case reveals that Dustin Prince was murdered because the killer thought he learned about his dark secrets and freaked out at the thought that a cop might be after him. Tragically, Prince didn't know anything. He and Maggie just happened to be on a date when they found the guy's cell phone and, had the murder not happened, they would have just handed the thing over and gone on their way.
      • In Case 4, there's an interesting variation at play. Matt wants to protect himself from being potentially implicated by the assassin he hired, who would have been the only remaining person to know about his involvement in the crime, so he kept blackmail material to get that assassin arrested if need be. This proves to be his undoing, as the assassin is so insulted at Matt's lack of trust in him, that he drops their contract and informs the court that he has a new target, i.e. Matt.
    • In Trials and Tribulations, this is a favorite reason of Dahlia Hawthorne's, for committing murder. She kills Doug Swallow because he figured out that she stole poison from the pharmaceutical labs and was trying to tell Phoenix, and it was also revealed that she'd been on her way to poison Phoenix because he unwittingly had the only piece of evidence that could implicate her in another crime. Earlier, she arranged for the death of her half-sister to prevent said sister from confessing to a crime they committed and also talks her boyfriend into a suicide pact so he'd kill himself before Mia Fey could get him to implicate Dahlia. Finally, she poisoned Diego Armando when he got too close to proving her guilt over the death of her half-sister.
    • Apollo Justice: Ace Attorney:
      • You don't learn it until the final case, but this is one reason the first case's victim was killed. He's really Zak Gramarye, the defendant in the trial where Phoenix lost his badge. He was the only person to know that he'd hired Phoenix at the last minute after firing his original lawyer Kristoph Gavin- which would implicate Kristoph as the true commissioner of the forgery that Phoenix was disbarred for presenting. The other reason was that his killer was mad at the guy for snubbing him.
    • This almost happened in the backstory to the second case, but the intended victim escaped and turned the tables. Pal Meraktis and Alita Tiala were the only people who knew that Wocky Kitalki had bullet near his heart and probably not long to live- Pal because he was the doctor who failed to take it out, and Alita because she was the attending nurse. They both kept quiet about it; Pal Meraktis didn't want to lose the Kitalkis' custom and Alita decided to marry Wocky so she could inherit his money when he died. Due to circumstances, Meraktis thought that Alita would tell Wocky about his condition, and tried to kill her so she couldn't. However, he failed to kill her by suffocation and she instead woke up and shot him.
    • The reason Drew Misham was murdered (and his daughter nearly killed) was because he was a forger who might have revealed the identity of his client Kristoph Gavin, who was so paranoid he tried to kill everyone connected to that case.
    • In Ace Attorney Investigations: Miles Edgeworth, Buddy Faith, Akbey Hicks, Deid Mann, and Cece Yew are all murdered for knowing too much about the smuggling ring and trying to reveal it to the authorities. To elaborate:
      • Buddy Faith stumbles upon Jacques Portsman trying to retrieve files that Ernest Amano, a member of the smuggling ring, can use against Quercus Alba, the mastermind.
      • Akbey Hicks finds evidence of smuggled goods in the cargo hold. Cammy Meele, a stewardess and the smuggler, quickly kills him to prevent him from bringing the information back to Interpol and blowing her cover.
      • Mack Rell and Manny Coachen murdered Deid Mann and Cece Yew, respectively, to keep them from testifying to the authorities. The former case is the one that is being tried during Case 4 of Investigations, ultimately leading up to Rell and Byrne Faraday's murders, while the latter is mentioned during that case.
    • Dual Destinies:
      • In case 1, Ted Tonate murders Detective Candice Arme because she sees him trying to steal a bomb to sell on the black market.
      • The third case has Professor Means murder Professor Courte because she learned he was accepting bribes from the parents of students, in exchange for giving them good grades.
      • This is the reason the phantom murdered Metis Cykes prior to the events of the game. She had a psychological evaluation that may have helped the police identify him, and he had to prevent that at all costs.
    • The first culprit of Spirit of Justice murders Paht Rohl because he knew that the Founder's Orb had been stolen. That would throw suspicion on the culprit, the person who would have the easiest time stealing the thing (a proper suspicion, because the culprit did steal it).
  • Danganronpa:
    • Danganronpa: Trigger Happy Havoc: The Mastermind attempts (but fails) to frame and execute Kyoko Kirigiri with a made-up murder scene because she stole Monokuma's special tool, which allowed her to explore locked areas of the school, which led the risk of her figuring out the Mastermind's identity and ending the Killing Game early.
    • It's a Recurring Element that there will be two victims in the third chapter- the intended one and one killed so they couldn't blow the killer's scheme.
  • In Double Homework, Dennis pries too far into Dr. Mosely’s professional life.
    Dr. Mosely/Zeta: He has has dipped his toe into a deeper pool than he can imagine. He will drown.
  • In The Eden of Grisaia the designer of the Thanatos system had a little accident after he tried selling the system to the terrorist Heath Oslo. Most of the people who are left don't really know the limits of the system as a result, which allowed Kazuki freedom to use the system in highly unintended ways until she blew her cover.
  • Extra Case: My Girlfriend's Secrets: The majority of Marty's deaths are caused by Sally going to extreme lengths to conceal her secrets. However, she doesn't start killing him until he discovers a truly incriminating secret, such as the existence of her basement.
  • Fate/stay night. Subverted. Shirou stumbles upon two Servants fighting, and one of them races to kill him due to the Holy Grail War's "no witnesses" rule. He's mostly dead when someone saves his life.
  • In Scrapland Vicus is killed because he was willing to share his evidence of The Archbishop's murder with D-Tritus.
  • In Shinrai: Broken Beyond Despair, this is the reason why Kotoba was killed. The mastermind behind the murder plan hadn't necessarily wanted to kill the victim but needed an additional accomplice, and Kotoba fit the bill, being someone who was easy to manipulate and someone the mastermind didn't mind killing. Once the mastermind is almost done with the plan, Momoko knocks Kotoba out, ties him up and sets the breaker room on fire to create a distraction while she hangs herself. It's possible to save Kotoba, but since he's in no condition to talk, it's up to Raiko to explain what happened.

  • Cashmere Sky: Abram is killed by Titus after he finds out that Lockridge's administration is manufacturing the poisonous fog that's taken over most of the world in order to keep control of the region and makes it clear to Lockridge that he intends to expose them. He anticipated this happening to him and wrote a letter to Archer before the murder can take place.
  • Girl Genius:
    • The entire Wulfenbach Vespiary Squad is targeted by the rest of the Wulfenbach forces after Herr Baron himself is infected by a slaver wasp and is compelled to destroy them. Thankfully, Tarvek and the Jägers salvage enough of the unit and their materials for them to continue their mission under a lower profile.
    • According to Tarvek, the Master of Paris encourages clubs to look over the code he uses to control the city in order to look for weaknesses that he can fix. Between Gil and Tarvek, they belonged to over twenty such clubs. The problem is if they learned too much about the code, the Master would drop their entire headquarters into a bottomless pit.
      Tarvek: The trick was to always make it out the door just as they started celebrating.
    • In the prose novel Agatha H. and the Siege of Mechanicsburg, some doctors praise the modifications made to a machine, unaware that Lucrezia was the one who did so. She notes to herself that she'd like to tell them she did it so that she could receive even more praise, but then she'd have to kill them to keep the secret of her true capabilities. She tells them anyway.
  • In Guilded Age, when one of his employees finds out about the players hidden in the basement who can't be removed from their Deep-Immersion Gaming, HR kills him.
  • The Last Days of FOXHOUND: Late in the comic, Scratch winds up translating a message that is just a giant bundle of information that would be very inconvenient for Liquid to have get out, so he snaps Scratch's neck. Scratch's partner Eddie, who doesn't know the information but is likely to react poorly to the sudden death of his friend, is dealt with offscreen by Mantis.
  • In Midnight's War, after Lord Dante Fitzalan receives a tour of a facility for the creation and weaponization of undead ghouls, he snaps the lead scientist's neck and feeds him to his own creations. He feels guilty about it, but is adamant that there are some things no man should know, or even imagine.
  • The Order of the Stick: Redcloak in #827 can't risk certain facts about a battle getting back to Xykon. Most of his soldiers in that battle were summoned and could be simply dismissed, but there was one goblin who needed to be dead. Luckily for Redcloak, the goblin in question was killed in that same battle, so was able to merely refrain from resurrecting him. And a few strips later he has Tsukiko killed by her own wights after she tells him she plans to blackmail him. Once he tells his real plan is not what she thought it was, she's too much of a liability to be allowed to live.
  • Schlock Mercenary: A lot of dirty secrets are about, and a lot of people get killed over it. Project Laz-R'-Us was a recurring element for this during the early years, and several characters were killed simply by knowing it existed.
    • In an early strip, a UNS intelligence officer is killed by his superiors during an intelligence briefing when he unwittingly lets slip that he might have learned details above his security clearance.
    • The Toughs fall afoul of this in a later arc, when they end up learning about the same thing. Ironically, by the same officer who did the killing in the above strip.
  • In Terra fighter pilot Alexis Hawke's CO has serious misgivings about their fighter squadron's mission to destroy a Resistance base. After two fighters and four crew don't come back (two Red Shirts were killed, Alex and Rick were shot down and rescued by the Resistance) he voices his concerns openly to the general, who shoots him.
  • Vampire Cheerleaders: In vol.1, Leonard becomes suspicious of Lori and her cheerleading squad and spends weeks secretly observing them. Once he had sufficient evidence, he confronted them and threatened to expose them as vampires. Lori's immediate response was to try to kill him, but he'd taken the precaution of eating plenty of garlic and drinking Listerine, which made his blood toxic to her. So she resorted to the next best thing: buy his silence by having the cheerleading squad screw him.

    Web Original 
  • Atop the Fourth Wall: Harvey Finevoice is able to figure out the clues in the book about the Entity at once. As such, he jumps to the top of its priority list to consume. The Ninja Style Dancer was grabbed earlier than the rest of Linkara's household for similar reasons.
  • This gem from The Best VRChat Moments on Twitch
  • Poor Desmond from Critical Role is privy to a lot of information about the Briarwoods, the couple that killed Percy's family. This knowledge almost gets him killed by invisible stalkers, but Vox Machina manages to save him in time.
  • Defied in Season 3 of the Dream SMP. Quackity considers killing Slimecicle for overhearing a conversation between him and Purpled because of this trope, but decides against it, instead choosing to utilize Slimecicle's Hidden in Plain Sight abilities for his own purposes, and recruits him as a spy for Las Nevadas.
  • Two Dark Angels in If the Emperor Had a Text-to-Speech Device are messily killed after their leaders blab out the existence of Fallen within their earshot. And then one of said leaders reminds the others those two were inducted into the Inner Circle last week and thus were qualified to know all about the Fallen without killing them. It's just that the others are trigger-happy paranoiacs.
  • Hunter: The Parenting: Big D is quite worried about this happening, which is why he doesn't tell his family most of what he knows about vampires- vampires have agents everywhere and are extremely touchy about Masquerade breaches. So if he tells his kids what he knows and they accidentally let slip even such innocuous info as the names of vampire clans and factions, they might be abducted and killed- and as an experienced hunter, D knows very well that even a single moment of dropping one's guard can lead to death.
  • Played for laughs in the ad break of In the Field's episode on weapons. Nordman possessed loads of knowledge based from information stolen online from users that don't have a VPN, and goes around crashing through windows and revealing said information. Just when he literally crashes a funeral to let them know they can save hundreds through regional pricing, he got shot in the chest. It turned out to be Shadowman, who was out to kill Nordman to keep the fact that he preferred playing Field of Tanks Mobile over Raid: Shadow Legends from being revealed.
  • In The Nostalgia Chick's review of Disney Princesses, she guesses that The Princess and the Frog was only created because Disney needed to expand their Princess line. A ninja is sent to silence her.
  • The Nostalgia Critic: In his review of Full House, the Olsen Twins try and kill the Critic when he attempts to tell the world his new knowledge that they're evil.
  • In Red vs. Blue, Tucker finds out by accident that Vic is the Mission Control liaison for both sides, and correctly concludes that the Reds and Blues are being played against each other by a third party. Vic hires Agent Wyoming to assassinate Tucker before he can tell anybody. Fortunately, Wyoming fails.
  • This is theorized to be one reason why the Slender Man goes after people. Of course, he's also been known to go after people for seemingly no reason whatsoever.
  • SCP Foundation: Those who access or attempt to access files that are higher than their clearance level authorize may face anywhere from having their employment terminated or having themselves terminated. Or an amnestic, if they're lucky when it comes to top secret info.
  • In Season 3 of Sonic for Hire, just as Sonic and the gang are about to head towards Casino Zone, Eggman decides The Noid's skills won't be required since he remembered that he never installed a security laser. After Tails pointed out that The Noid was already debriefed on the heist, Sonic immediately shoots him in the face.
  • A mysterious murder committed for this reason kicks off the plot of the Web Serial Novel Tremontaine. It's not revealed until later what dangerous secret the dead man knew: that the woman known as Diane Roehaven, Duchess Tremontaine, has actually been an imposter for the past two decades — a servant girl who couldn't deal with her Rich Bitch employer any longer and pulled a Kill and Replace on her, taking advantage of their uncanny resemblance. The dead guy, apparently Too Dumb to Live, tried to blackmail her with this secret.

    Western Animation 
  • In the American Dad! episode "Stan Smith Is Keanu Reeves as Stanny Utah in Point Break", Stan happens to be standing on a beached jellyfish that attracted wolves, who are in turn being hunted by poachers. One of the poachers says to Stan that he's seen too much and points his gun at him.
  • Joked about in Avatar: The Last Airbender when Aang and a post-Heel–Face Turn Zuko discover that the ancient Sun Warriors, thought long extinct, are actually still extant and just living in seclusion. The Sun Chief declares that because they have learned this secret, they know too much and cannot be allowed to leave alive... then he chuckles and admits he's just messing with them. After an intensely awkward Beat, he adds "but seriously, don't tell anyone".
    • While Ozai claims he banished Ursa as punishment for her treason, Avatar: The Last Airbender - The Search makes it clear that this trope is the real reason why he sent her away. Ursa made a Perfect Poison which Ozai used to kill Azulon, and once the deed is done Ozai sends her away so she never gets the chance to make the poison again and use it against him.
  • Batman: The Animated Series: In her debut episode, as far as Poison Ivy knows, Batman is the only other person aware of her poisoning Harvey Dent, thus necessitating that he too receives a goodnight kiss.
  • In Batman Beyond: Said in its entirety by Inque about Terry McGinnis. It is also the motive behind Derek Powers's murder of Terry's father, which prompted Terry to become Batman.
  • Codename: Kids Next Door: After Leona finishing explaining to Sector V about how she discovered the Fountain of Youth, she immediately tries to kill them with the fountain's water because they now know her secret.
  • Disenchantment: Apparently every time the elves hold a meeting where they come up with a plan they don't want anyone to know about, they throw Blabbo in jail to prevent him... well, y'know. Blabbo points out there is a simpler solution.
    Blabbo: In the future, just don't invite me to these things!
  • Futurama:
    • The Robot Elders of Chapek-9 try to kill Fry, Bender and Leela for learning they don't actually have anything against humans, but just use them as a scapegoat to distract the robots from other problems. Like a corrupt government of incompetent robot elders.
    • A robotic toilet the crew is throwing away offers them "Happy Poopy Time" if they spare it. Fry simply says "You know too much."
    • In "How Hermes Requisitioned His Groove Back", Bender catches Morgan Proctor making out with Fry and threatens to tell her bosses at the Central Bureaucracy, leading her to remove Bender's personality chip and ship it to the Bureaucracy.
  • At the end of the Gravity Falls episode "The Stanchurian Candidate", Stan's bid for mayor is torpedoed by his own criminal record; one such crime included "first-degree llamacide", to which Stan responds, "That llama knew too much!"
  • Parodied in an episode of Jackie Chan Adventures, appropriately titled "The Chan Who Knew Too Much". A cabal of wizards repeatedly states that Jackie "knows too much" when he finds out any of the cabal's secrets... their name, their plans for Stonehenge, or even the location of the bathrooms in their secret lair. ("He's privy to our privies!") To make it even better, Jackie really didn't know anything at all about when he first accidentally dropped in on all of them — for all he knew, they could have just been wannabe Satanists or something. They pretty much told Jackie everything themselves, e.g showing him that they knew magic by trying to kill him with it. It then gets gloriously lampshaded when Jade claims to know their magic words, but can't cast their spells. The man gloats that she 'knows nothing' and Jackie cries out, "That's what I've been trying to tell you!"
  • Spoofed in the Looney Tunes short "Bugs and Thugs", where gangster Rocky decides that Bugs "knows too much" when he, among other things, correctly identifies Carson City as the capital of the state of Nevada.
  • Played with in an episode of The Penguins of Madagascar where the penguins are trying to bury shredded documents, only for Julian to mistake them for puzzles and put one together showing a penguin shaking hands with a Sasquatch and the King of Sweden, causing Kowalski to say the trope name word-for-word.
  • In Rick and Morty, this is how the Citadel of Ricks deal with Ricks who have been captured by the Galactic Federation for their secrets. They almost succeeded in killing our Rick, but not before he switched bodies with someone else.
  • In a Robot Chicken skit, while the Smurfs are remembering other Smurfs that died on Memorial Day, Handy Smurf notices that most of them were related to a once-popular trend that soon became outdated. When Papa Smurf is asked that if the victims all died of natural causes (as in not being assassinated by a sniper), he decides to have Gargamel's cat Azrael eliminate Handy for knowing too much. That is until Handy managed to kill the cat and get revenge on Papa Smurf.
  • Played with in The Simpsons:
    • Homer followed his coworkers to the Stonecutters' headquarters. He gets inside by falling through the skylight and is instantly surrounded. They declare that he has seen too much and must pay "the ultimate penalty". So they toss him out the front door.
    • In "New Kids on the Bleech", after Lisa discovers the Navy's conspiracy to recruit people via Subliminal Seduction, Lt. Smash says ominously "Well, now that you know, I'm afraid I can't let you leave." But Lisa already left.
  • In The Spectacular Spider-Man, Punch-Clock Villain Doctor Otto Octavius is entirely correct to fear that someone will discover his involvement in the creation of Supervillains made to antagonize Spider-Man. Indeed, Green Goblin engineers a Freak Lab Accident to silence the doctor for good. The catch? Octavius lives, though he's become much less meek and a lot more megalomaniacal. Unfortunately, the newly-christened Doctor Octopus assumes Spider-Man is the culprit.
  • Star Wars: Tales of the Jedi:
    • "The Sith Lord": Yaddle stumbles upon Dooku meeting up with Palpatine on the day of Qui-Gon's funeral, leading to her death on the future Emperor's orders to prevent the Jedi from squealing like a rat and to cement Dooku's loyalty to him.
  • Star Wars: The Clone Wars:
    • "Cloak of Darkness": Ventress' orders are to either rescue Gunray, or kill him if that's not possible given how many secrets he knows.
    • During the "Orders" arc, ARC trooper Fives discovers the existence of an organic chip implanted into each clone trooper's brain at birth, enabling one to command the clones to commit any action without hesitation, including killing the Jedi. When he attempts to present his findings to the Chancellor, he is secretly drugged by Nala Se, the lead scientist responsible for the organic chips to make him appear insane. Furthermore, Palpatine reveals that he's the one who orchestrated the implantation of the organic chips, and has Fives hunted down and ultimately killed before Fives can reveal the truth to the Jedi.
    • A heroic example in "Carnage of Krell", after arresting Pong Krell for treason, Captain Rex ultimately decides that he's too much of a risk to keep alive in case the Umbarans take back their base. Rex can't bring himself to do it, but fortunately Dogma finishes the traitor off.
  • Star Wars Rebels has a rare heroic example. During the final confrontation between Obi-Wan Kenobi and Darth Maul, Obi-Wan starts off simply verbally refuting all of Maul's statements. However, the instant Maul realizes who Obi-Wan is protecting on Tatooine, Obi-Wan draws his lightsaber, making it clear that Maul cannot be allowed to leave Tatooine alive with the knowledge of who Luke Skywalker is.
  • Star Wars Resistance: In "The Children from Tehar", the First Order is after the titular children because they're the sole survivors of one of their atrocities, and could tell others what they've been doing.
  • In Baxter Stockman's debut in Teenage Mutant Ninja Turtles, after he's made a master control for the hundreds of Mousers Shredder forced him to make, Shred-head decides that "He knows too much" and sends his Foot Soldiers to eliminate Baxter. Only the Turtles' timely intervention prevent the Foot from succeeding.
  • A Thousand and One... Americas: In the twelfth episode, Chris is told that bronze is a valued metal in the Andean city of Tiahuanaco, and the secret behind its making is a secret. He casually remarks that bronze is simply an alloy made of copper and tin, but this is because the fact is well-known in his era in the present, not the past era he's dreaming of at that moment. When he sees how alarmed his guide is and later how upset the local people (including the priest who watches over Tiahuanaco) are, he realizes the gravity of his mistake.
  • Transformers: Animated has Blurr, who was offed by the traitor for knowing too much.
  • An episode of The Venture Brothers has Dr. Orpheus about to reveal the truth of why The Monarch was arrested. As he's about to spill the beans, Phantom Limb calls in the Strangers to freeze everyone in ice and administer either memory wipes or hypnotic suggestions to the room, thereby making Orpheus declare that Monarch is guilty of crimes he didn't commit.

Alternative Title(s): You Know Too Much, She Knows Too Much, They Know Too Much


Ruins of War

Rampart kills Wilco when he's unwilling to falsify a report for him

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5 (15 votes)

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Main / HeKnowsTooMuch

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