In real life, letter openers are designed for opening envelopes and nothing else. They're wide and blunt, can be made of anything from wood to metal to plastic, and are rarely sharpened, since no one wants to cut themselves opening their mail. In the world of fiction, however, letter openers come in one variety: metal, sharpened, and conveniently placed. If one is seen, it's nearly always for use as a weapon, with opening mail being a distant second. In truly gratuitous circumstances, it might be an Absurdly Sharp Blade. Some might use it as a Hidden Weapon for circumstances when carrying a knife would be inadvisable.
This can be Truth in Television, as letter openers have been used in murders and attempted murders. As noted in the real-life section below, however, these letter openers were usually sharpened beforehand.
Often a Sub-Trope of Improvised Weapon, Absurdly Sharp Blade and Conveniently Placed Sharp Thing. May serve as a Chastity Dagger. Compare Shear Menace and Combat Haircomb for other forms of improvised blades.
- In the anime of The Garden of Sinners, Mikiya stabs Alba in the shoulder with a letter opener. Unlike most examples of this trope, it's realistically too small and blunt to do real damage.
- The Bolt Chronicles: In "The Murder Mystery," the Director is killed when he is tripped up by a strung piece of rope and falls onto a letter opener standing blade-up on the floor.
- A Dovahkiin Spreads His Wings: Cersei Lannister stabs her father Tywin to death with a letter opener to the heart in order to consolidate her coup of King's Landing.
- The Negotiationsverse: In the Choice chapter "Abolition," after the Equestrian Freedom Fighters have failed to steal the Scroll of Ascension, Dusty Pages reveals her true colors as a traitor and the EFF's informant by trying to stab Twilight in the neck with a letter opener when her back is turned. Twilight simply grabs the tool using her telekinesis, confronts Dusty, and has her arrested.
- Richmond in Absolute Power gets this twice, once by Christy when he's trying to rape her, and fatally in the end.
- Breakdown has Jeff cut through his bonds and fight with a letter opener he pilfered from a bank. He was bound with duct tape, making it somewhat plausible that a letter opener could do the job.
- In Dog Soldiers, a woman gives her fiance a sharp, silver letter opener to celebrate his new promotion, saying "Every knight should have a sword". At the climax, Cooper finds it with his body and stabs Ryan with it, removing his invulnerability so he can finish him with a headshot.
- Chris stabs Missy in the eye with a letter opener in Get Out (2017).
- Naked Killer: Kitty's first onscreen kill as an amateur assassin in her target Mr. Bee's office has her being held down by a mook while Bee tries to rape her; but in the struggle, Kitty managed to grab a nearby letter opener and stab the mook's jugular, before shoving her weapon into Mr. Bee's crotch.
- In A Shot in the Dark, as part of his growing Sanity Slippage born from anger towards Clouseau's stupidity, Commissioner Dreyfus starts accidentally injuring himself shortly after taking Clouseau off the Gambrelli case, twice, forcing him to reinstate Clouseau while he's getting his injuries treated. First, he accidentally cuts off his thumb with a cigarette guillotine, and then later, he's walking around with a letter opener whilst ranting about Clouseau's incompetence being the only reason M. Ballon wants him on the case to cover up his affair with murder suspect Maria Gambrelli, only to cross his arms in exasperation, forgetting about the letter opener until he's already stabbed himself with it. Taking it very calmly, Dreyfus immediately phones Clouseau to put him back on the case, whilst getting his wound plastered and bandaged over.
- In The Finishing School Series, Mademoiselle Geraldine's girls are trained in hidden weapons, with a sharpened letter opener being among them. Sophronia uses it to check the basket of her airdinghy by stabbing through the wicker.
- Sherlock Holmes: In "The Golden Pince-Nez", Holmes quickly guesses that a professor's secretary was stabbed through the heart with a letter opener by unfortunate accident: as the murderer lost their titular high-strength glasses in a struggle against him, they must have grabbed the first thing to hand and swung blindly. He also deduces the professor is hiding the murderer, who emerges to confirm Holmes' assertions, says she took poison, and asks that they finish the job: stealing back letters that would free a political prisoner in Russia. Holmes does so.
- Lou of Brand New Cherry Flavor has a letter opener he calls "The Final Cut". Mary uses it to kill Code by stabbing him in the eye.
- Buffy the Vampire Slayer: Subverted, when Giles is turned into a demon, Buffy stabs him with a letter opener. He's fine.
- In Charmed (1998), Prue stabs an attacker in her dream with a letter opener. When she wakes up, the blood is still there.
- A letter opener was sometimes a suspected weapon in the game show Cluedo.
- In the Inspector Morse episode "Service of All the Dead", one of the victims is stabbed with a crucifix-shaped letter opener.
- In the Law & Order episode "Big Bang", a woman tries to open a package with a letter opener, and it explodes, flinging the letter opener into her neck. A technician later puts it down to bad luck: the bomb itself wasn't powerful enough to kill her, but the letter opener was.
- Law & Order: Special Victims Unit: The episode "Ridicule" has a male stripper being raped by three powerful women, one of them threatening to kill him with a letter opener. The defense attorney gives him nothing but grief, while some of the men in the squad are skeptical, Cragen, Olivia, and Alex all point out that his panic was valid and fear is a natural response.
- In the Psych episode "Office Space" a certain Mean Boss yells at his secretary and throws a letter opener at her. That same letter opener is later used to kill him. She's not the killer, it was just some Laser-Guided Karma on his part.
- Wendy Watson of The Middle Man got her job when she was attacked by a monster and responded by grabbing a letter opener and leaping at it.
- In Arknights, Natalya (Operator Rosa) keeps a letter opener from her noble family's mansion as a memento. It's sharp enough that she uses it to self-harm in conjunction with suicidal ideation. The day she decides to step out of the shadow of her past, she gives the letter opener to the Doctor as a pledge to move forward.
- In Criminal Case: World Edition, a letter opener is the murder weapon in the final case.
- Hitman: The letter opener is one of many melee weapons that can be found in the World of Assassination Trilogy. Strangely, the letter opener is considered an illegal item, and openly carrying one will be treated the same as if Agent 47 were holding an actual knife or gun, even though it's no more or less lethal than other obtainable household items like screwdrivers or scissors.
- Vampire: The Masquerade - Bloodlines: Prince LaCroix has a letter opener on his desk throughout the game. Unless you side with him, you grab it in the ending cutscene and demonstrate your displeasure in him via a Slashed Throat and Agonizing Stomach Wound. Being a vampire, he survives, but it takes the fight out of him.
Malkavian Player Character: Give you a massive chest wound? My pleasure!
- At Dead of Night: A letter opener is sharpened to use against Harvey, which resulted in him bleeding out at the backstage, with his death being ruled out as an act of self-defense rather than murder.
- World of Warcraft: Lampshaded by an archaeology project, a Highborne letter opener, which notes such items were largely useless except as a weapon of last resort in situations where one isn't allowed to carry a dagger.
- A letter opener is one of the many weapons available in The Ship: Murder Party.
- Elements of Justice has a letter opener being used as the murder weapon for case 2. Except actually not; the corpse was stabbed after the murder to implicate Sugar Stamp. Somehow the perpetrator managed to get said letter opener through his skull, something that would be difficult for many actual knives.
- Whack Your Boss features this as one of the many methods of killing your aforementioned boss. Selecting the letter opener will see your employee player character plunge it into the boss's stomach; at which point his guts will spill out. This is followed by the employee then stabbing the boss in the throat as a finishing move before he collapses on top of his own guts.
- The Joe Cartoon Flash Game "The Boss" also incorporates the usage of letter openers in another title that revolves around hilariously abusing a boss. Unlike Whack Your Boss, however, the point behind the usage of letter openers is to use them in the lieu of throwing knives while the boss is helplessly strapped to a bullseye target. This is done in order to torture him with threats before you switch to more unconventional methods as a form of escalation that will ultimately get the job done for you.
- Robot Chicken: In the skit "Office Kombat", when Jim faces Nancy as his opponent, he kills her with a letter opener in the eye.
- Discussed in the The Simpsons episode, "Trash of the Titans"; when Homer wins the election for Sanitation Commissioner against Ray Patterson by making wild promises, the latter is forced to clean out his office. When Homer and Patterson next meet, Patterson tells Homer "If I hadn't already packed my letter opener, I'd give you such a stabbing!"
- Patrick Henry symbolically stabbed himself with a letter opener at the end of his famous "Give me liberty or give me death!" speech, proving this trope is Older Than Radio.
- This trope is often invoked by making custom letter openers shaped like swords.
- A sharpened letter opener was used in an assassination attempt on Martin Luther King Jr., piercing his chest and barely missing his aorta. It had to be extracted with a clamp as it was sharp enough to cut the surgeon's hand.