History Main / PsychoKnifeNut

* ''WebVideo/RatsSMP'': [[{{Hypocrite}} In spite of being designated as the Safety Rat]], Jimmy is decidedly one of the more… ''unhinged'' rats, shall we say, and has been constantly running around with a knife since Day 1 and threatening humans every other day, and is the only rat ''with a non-rat body count''. He is also the only rat who endorses Scott's RevengeBeforeReason plan against the cats when he first hears of it, though his opinion immediately shifts to opposition when it's clear it's not working as intended.

* The original ''VideoGame/TimeCrisis'' has TheHeavy, Sherudo Garo, who's an expert in throwing knives and in his introductory cutscene, happily taunting the kidnapped Rachel [=McPherson=] by holding his knife on her face, giggling all the way.

* ''VideoGame/Undertale'': The final and most powerful weapon in the game is the Worn Dagger, but on the Genocide Route it becomes the vastly more powerful Real Knife (as opposed to the Toy Knife). Given that it presumably belonged to the First Fallen Human, and said human was [[spoiler: stated as sometimes making a "creepy face" and described as "not the greatest person," it's possible that they qualified as this.]] Given that by the end of the Genocide Route, both the player character and [[spoiler: the First Fallen]] have gone utterly insane, they probably both qualify as this even if they didn't before. Obviously, it's made a lot less ambiguous in most fan works.

* ''LetsPlay/RatsSMP'': [[{{Hypocrite}} In spite of being designated as the Safety Rat]], Jimmy is decidedly one of the more… ''unhinged'' rats, shall we say, and has been constantly running around with a knife since Day 1 and threatening humans every other day, and is the only rat ''with a non-rat body count''. He is also the only rat who endorses Scott's RevengeBeforeReason plan against the cats when he first hears of it, though his opinion immediately shifts to opposition when it's clear it's not working as intended.

* ''VideoGame/Undertale'': Many fans interpret [[spoiler: Chara]] this way.

* Part of Ryan Haywood's TokenEvilTeammate shtick in Creator/AchievementHunter videos is that he ''loves'' knives and his first objective in games is to murder. He also keeps a cup filled with them at his desk.
-->'''Ryan:''' Why do I need a cup full of 37 knives? I don't, ''but I like it''!

--> EMERGENCY. MACHETE.

* ''VideoGame/OMORI'': Both Omori and Sunny use knives as their primary weapons. Add this to [[AxCrazy the way Omori looks when Manic]], and it's no surprise that much of the fandom sees him this way.

* ''Film/DieHardWithAVengeance'' has [[TheDarkChick Katya]], and to make clear she's very psycho, as the baddies invade the federal reserve, she repeatedly slashes a guard until Simon holds her back saying "I think he's dead, my dear."

* ''Manga/RecordOfRagnarok'': Jack the Ripper is a SerialKiller who uses a nigh limitless number of knives in his fight against Heracles.

** Bob Velseb is a [[ImAHumanitarian cannibal]] SerialKiller with a whole host of knives and knife sharpeners hidden in a toolbelt under his sweater. His main weapon is a carving knife, and he sharpens it when near his prey to intimidate them.

** Udai Taxim is a dangerous convict who likes to use knives.

* In ''Film/Masquerade2021'', Rose stabs [[spoiler: Daniel]] repeatedly with a kitchen knife, and there are several lengthy shots of the leather-clad intruder holding the blood-smeared weapon just to emphasize how crazy this woman is. [[spoiler:Subverted with the reveal that Rose is doing this out of revenge for Daniel killing her parents.]]

One reason for this is that knives are ''scary'', as a single glimmer from its profile in AxCrazy hands has been known to provoke screeches of horror (that and the possibility that they're more painful than any gunshot will ever be). Another reason is that knives are very accessible -- if a once-sane person suffers from SanitySlippage, chances are they already have several sharp knives in their house with which to get their killing spree started once their mental state reaches "murderous". Knives are also relatively easy to deal damage with, and a great way to release pent-up rage and hatred. Once a crazy knife-wielder gets close enough to enter a stabbing frenzy, it's almost impossible for their victim or those close by to stop them.

* Clove from Literature/TheHungerGames has many knives and is very skilled at throwing them. She is also quite sadistic, what with trying to torture Katniss to death and all.

* ''WebAnimation/SpookyMonth'': Bob Velseb is a [[ImAHumanitarian cannibal]] SerialKiller who wields a huge knife and sharpens it menacingly when closing in on his prey.

Subtrope of WeaponBasedCharacterization. Related to DeviousDaggers, SinisterSwitchblade, SinisterShiv, MacheteMayhem, KukrisAreKool, and BayonetYa. No relation to GunNut despite the similar names.

* ''LightNovel/{{Durarara}}'': [[spoiler:[[{{Yandere}} Haruna Niekawa]], while possessed by [[EvilWeapon Saika]], uses a knife to stab people with in order to [[TheVirus spread Saika's "children"]] before she snaps out of it.]]

* Asakura Ryouko, the GirlWithPsychoWeapon in ''LightNovel/HaruhiSuzumiya''. Worse yet, it's a combat knife with nasty spikes on the backside. And Asakura can be scary. [[UncannyValleyGirl Very scary.]]

* ''LightNovel/ReZero'': Elsa Grandhirte is an AxCrazy assassin who fights with [[KukrisAreKool kukri blades]].
* ''[[Manga/Reborn2004 Reborn!]]'': Belphegor. He's a knife-wielding psychopathic assassin in the Varia.