A fictional character who is insane (in the psychotic, out-of-touch-with-reality way) is usually also violent. Thus, in typical TV-land logic, if you become psychotic, you must also become violent—even if you never were before. A character who already resorts to violence will turn on their friends instead of fighting whatever enemy they usually fight. (Conversely, a villain or antihero who engages in unnecessary violence will often be called "psychotic" as an insult both in- and out-of-universe, even though that character might be clinically sane.)
What's more, the fictional psychotic will not only be violent, they'll actually be more lethally effective than a sane person. Count on the villainous psychotic to be a nigh-unstoppable assassin who's mastered Offscreen Teleportation rather than, say, a poor deluded individual uselessly arguing with or attacking their own hallucinations, or getting caught after committing a crime they were too confused to know was even a crime at all. Expect plenty of ridiculously heightened abilities, ranging from super-strength to freakish imperviousness to pain.
This is usually used to enhance the frightening aspect of a character since psychosis makes them unpredictable and their behavior unfamiliar. In a fight, they have terrifying Confusion Fu. Many slasher-film villains are insane; most characters perceived as psychotic are also violent and unpredictable. The very connotation of "escaped lunatic" is that of a violent person, an urban-myth trope that goes back as far as the first mental asylums. The same goes for "psycho", "madman", and "insane", all of which commonly imply violence or evil (or both).
Although over one-third of the world's population qualify as mentally ill at some point, media coverage of mental illness is mainly comprised of extremely negative and derogatory depictions — as you can see on TV Tropes itself. Incompetence, violence, or criminality are generally the forms that appear in fiction, with far less depiction of 'uninteresting' conditions such as depression, catatonia, or 'harmless' OCD. In 1999, characters in prime time television portrayed as having a mental illness were depicted as the most dangerous of all demographic groups, with 60 percent shown to be involved in crime or violence. Such negative depictions, including in children's cartoons, are thought to contribute to stigma and negative attitudes in the public and in those with mental health problems themselves, although more sensitive or serious cinematic portrayals have increased in prevalence.
This trope has some roots in Truth in Television, though of course different mental illnesses will differently affect a person's propensity towards violent crime: some illnesses (like antisocial personality disorder) have violent behavior as a symptom, whilst others (such as depression) actually make a person less likely to commit a crime. Overall, people with mental illnesses do commit slightly more violent crime than average. However, it's not anywhere nearly as common as media would imply: Mental illness is an extremely weak predictor of violence, to the point of uselessness even when compared to simple demographics like being young or male. Mentally ill people are also more than eleven times more likely to be victims of violence (although it should be noted that the people in that statistic were seeking help, whereas the ones who were not were most likely not). Alcohol and drug abuse are associated much more strongly with violence, and when you account for the increased prevalence of drug and alcohol abuse among those with mental illnesses, the extra risk of violence for mentally ill people overall vanishes completely... but that's not as interesting.
This is becoming more of a Discredited Trope, thankfully, as more writers are leaning towards interesting motives for violence, but still lingers on in the Horror genre.
See also: Ax-Crazy. Compare it with Sanity Has Advantages. Contrast Loon with a Heart of Gold.
- Alois Trancy in the second season of Black Butler. He's basically Ciel Phantomhive behaving horrifically and in the first episode he stabs out one of his maidservant's eyes with sadistic amusement for simply looking at him. It warrants mentioning that he stabs out her eye... with his fingers. Why? Because he's just that crazy.
- A few characters in Elfen Lied, namely Lucy and Mariko. And the cruel kids from Lucy's past who were clearly psychopaths who beat Lucy's dog to death while making her watch to get a reaction out of her.
- Andrea Cavalcanti/Benedetto in Gankutsuou is an effortlessly charming fop who happens to also be a wild-eyed rapist with daddy issues. Best demonstrated when he tries to rape his fiance Eugenie and suddenly attacks Haydee.
- Averted by the titular character in Goblin Slayer. A few characters note that he's an obsessive freak who's not all there, and even Cow Girl's uncle warns her to keep her distance as the boy she knew back then is gone. But Goblin Slayer remains calm and cordial in his relationships, and at the end of the day, he's still a trusted Silver-rank member of the Adventurer's Guild.
- Farfarello of Knight Hunters falls under this, particularly in the backstory. As a child, he snapped and killed his whole family, despite apparently being a perfectly normal kid beforehand.
- Hidan of Naruto, though his "insanity" takes the form of membership in a cult that worships a god of murder and powers that combine violent self-mutilation with immortality and sympathetic magic. Since all the major characters are ninja, violence is a given.
- Chiri Kitsu of Sayonara, Zetsubou-Sensei started out as mostly a Control Freak / Neat Freak, but over time becomes defined by violent psychopathy and is presented as a Serial Killer.
- Taken to the extreme in Soul Eater. Insanity, fear, madness, etc. is basically this universe's Virus. You can be infected with insanity, and being insane means that you have the urge to hurt things. By killing humans and eating their souls (which is what insane people do, apparently), one can actually become an Eldritch Abomination. This is how the series' Big Bad Asura became the Big Bad — he was a nervous person who succumbed to his fear, took the life of an innocent human, and consumed their soul in order to gain power. (Ironically enough, consuming the soul of a corrupted, insane person in this series has no negative side effects whatsoever.)
- In Sword Art Online, this seems to be a dime a dozen for the villains, so much so that if you're a villain, you're also Ax-Crazy. Not only are they violent but are also psychotic to varying degrees, such as Vassago Casals/PoH, the Death Gun trio, and Gabriel Miller/Subtilizer.
- Zig-Zagged in The Adventures of Tintin, A plot point in one of the biggest story arcs (Cigars of the Pharaoh — Blue Lotus) is the Rajijah juice, a poison that causes madness. Several characters are driven mad by this poison, and the most common symptoms are just that they become a total Cloud Cuckoolander. Only two characters driven mad by this show any violent tendencies — Professor Sarcophagus, who was influenced by a Fakir after having already gone mad, and Didi, who encourages people to find the way, and says he'll cut off their head. However, he is eventually cured, though not much is known about the other victims of the Rajijah Juice.
- Batman villains are widely regarded as among the most psychotic and violent in all of comics and thus are serial representatives and offenders of this trope.
- This results in part because of Characterization Marches On. The original Batman villains were master criminals typical of pulp villains with no real motivations. The first Joker dressed in white paint and didn't have silly gag-based antics. After the '50s, when comics were subject to Bowdlerization, The Joker became a harmless villain with gag-based antics celebrated in the Adam West show. When Dennis O'Neil, Steve Engelhart, and other writers sought to make the Joker menacing again, they had to justify the gag-based elements which had become The Artifact as well as other motif-themed criminals such as The Riddler which became famous thanks to Batman (1966). Their solution was Hollywood Psych, and they added Arkham Asylum into the mix. Since then, all of Batman's villains were described not merely as supervillains but as psychopaths.
- Frank Miller's The Dark Knight Returns partly plays this straight and partly parodies it, by showing how absurd Batman's conflict with supervillains becomes when made into a discourse among the popular psychology and sociological analysis of prime time cable news. Popular psychologists and careerist shrinks like Bart Wolper try to cure the likes of Two-Face via plastic surgery that repairs the bad half of the face. It turns out to be the wrong half; the real Harvey Dent was the scarred-out part of his face, representing his guilt and self-loathing. The book also shows Joker closer to the original Bill Finger characterization as a joyless psychopath who speaks in a Creepy Monotone, although it does this by playing up the Foe Romance Subtext element to whole new heights. Batman himself in Frank Miller's books is shown to be somewhat of a functional madman most of the time.
- Alan Moore wrote The Killing Joke in part to reconcile all the elements of the earlier Joker origins with his new characterization as a psychopath, in the process he raised the question of whether Joker can be truly held accountable for his actions on account of his mental illness, whether he can potentially be cured. While the "one bad day" element of Joker and the book's depiction of him as Batman's Shadow Archetype has endured, Moore felt that introducing realistic psychology is pointless with the function that Joker, as an entertaining supervillain, is supposed to perform.
- Grant Morrison has repeatedly raised the possibility that, whatever is going on in the Joker's head, it isn't madness as we currently understand it, but something much worse. John Carpenter's Joker: Year of the Villain one-shot is written from the perspective of a young man who is realistically mentally ill, and who comes to realise that he and the Joker are not the same.
- Two-Face wasn't evil until one side of his face was ruined and (depending on the version) his insanity either began or became much worse. In fact, most Batman villains tend to fall into this category... with the exception (usually) of Humpty Dumpty, who saved Batgirl from falling off a building, fixed her dislocated shoulder, and went quietly to the asylum.
- Mr. Freeze is usually one of the few clear aversions in Batman's rogues gallery despite usually being incarcerated at Arkham because the facility can cater to his odd medical needs, as he's not "mad" in the least and is instead just a cruel pragmatist driven by anger, grief, revenge, and hatred. He was turned into a straight example for the New 52 driven by his obsession with Nora who in this reality he's never known and his delusions of a relationship with her (and then soon reverted to his previous version, since the change was highly unpopular).
- Deadpool becomes more unhinged than usual during the Black Box story arc of Cable & Deadpool. Even though he can't remember it later, it is revealed that he murdered a terrorist who was living on Cable's island. When asked why he did it, he replies that he doesn't know. Since his mind is more out-of-whack than usual, he just killed for no reason. However, Deadpool was pointlessly violent long before he was portrayed as insane.
- When Harry Osborn became the second Green Goblin, he was not under influence of the Goblin Serum (though it was later retconned that his father did give him some), but merely under the influence of drugs and insanity.
- Darryl Cunningham's comic book Psychiatric Tales is an attempt to demystify mental illnesses and change their perception in media and in society. This trope is played straight in chapter "Antisocial Personality Disorder" (also known as "Mad Or Bad" on Darryl's blog). Other stories are actually an inversion, stating that people suffering from mental illnesses are more likely to be a victim of crime or harm themselves rather than anyone else.
- In the last arc of Runaways, Klara suffers a panic attack and lashes out at her teammates, resulting in the destruction of the team's house. To be fair, most of the damage to the house comes not from her personally, but from the plants that she summons (over which her control depends on her emotional state), but she herself punches and kicks Nico Minoru several times, causing the latter to resort to Mind Rape to force her to calm down.
- In the second volume of The Unstoppable Wasp, A.I.M. attacking G.I.R.L. sets off Nadia's undiagnosed Bipolar Disorder. When the rest of Nadia's friends confront her upon realizing something was wrong with her, they end up aggravating her problems (which were already bad due to sleep deprivation) and she goes violent on them. When she comes down from that high and realizes what she's done, she's nearly Driven to Suicide, but is saved by one of her other friends.
- The Vision (2015):
- A series of traumas undermine Virginia's mental health, and by the middle of the series, it's clear that something is psychologically wrong with her. She later kills Victor out of revenge for Victor's accidental murder of her son, then savagely kills Sparky as part of a magical formula.
- Victor Mancha has a vibranium addiction, which has had a detrimental effect on his mental health. Victor accidentally kills his nephew Vin while high on vibranium, despite vibranium supposedly being a painkiller for robots.
- Watchmen plays with this in many ways, by averting both Hollywood Psych and Single-Issue Psychology:
- In the book, there are very few supervillains, and the ones who were, like Moloch, quit a long time ago when the first super-powered hero Dr. Manhattan arrived on the scene. The alleged heroes, however, are full of neuroses. The Comedian is The Sociopath, a highly amoral Blood Knight who tries to justify his vision by repeatedly telling idealistic do-gooder heroes that At Least I Admit It. The backstory reveals a more complex, guilty, lonely, and pathetic individual underneath that cynical facade.
- Rorschach is a Sociopathic Hero, described by Moore as "Batman without the excuses". He lives alone, prowls the streets and bars, believes in all kinds of conspiracy theories, and sees himself as the Only Sane Man. He was already violent and unstable even before a certain dog incident but after that, he becomes even more violent, in his own words explaining that he had been merely soft before because he let his victims live.
- Malcolm Long, a sympathetic and realistic psychologist character, is himself hurt and struck by Rorschach's grim Black-and-White Morality after hearing about his Despair Event Horizon. What makes Rorschach different is that he's not as consistent as he believes as seen in the end when he opposes Adrian Veidt's Utopia Justifies the Means atrocity using the same arguments that Rorschach used in justifying Harry Truman dropping the bombs on Hiroshima and Nagasaki.
- Nite Owl is more sane than other costumed heroes, but he does admit to Laurie that the costumes do give grounds to act out harmless Casual Kink as seen when he and Laurie have sex in costumes after they couldn't make out in civilian identities.
- Subverted in 30 Days of Night: Bloodsucker Tales with Lex Nova, a deranged vampire who believes himself to be a private eye and goes on brutal rampages the second he tastes blood. He's actually a genuinely heroic Friendly Neighborhood Vampire who only feeds on goats and directs his rampages on other, malevolent vampires and a group of misogynistic Serial Killers.
- Diamond, an OC from Akatsuki Kitten: Phoenix Corporation Overhaul. The difference is that she is very aware of it, and came to terms with it long ago. If pressed for an explanation other than insanity, she'll blame her extreme bloodlust on her family history: she used to be Renesmee Carlie Cullen.
- Apprentice and Pregnant: Ivypaw trying to murder her best friend's brother for yandere reasons is excused because she has an unmedicated mental illness that she inherited from her mother. She's punished, but it's not as severe a punishment compared to what she would have been given if she had been in her right mind.
- Bag Enders features Frodo. Even Gandalf is scared of him.
- Bird plays with this concept. While many patients are dangerous, the danger has no direct correlation to insanity. Sveta is very violent, but perfectly sane, as it is entirely her power's doing. Burnscar is somewhat less violent but also has mental and emotional problems to match. Taylor is initially very hesitant to use her powers in an effort to avert this in herself.
- Deconstructed in Cheating Death: Those That Lived with Mascara from District One, the daughter of Victor and Princess Court. She is severely mentally ill, and although she could have received treatment for it and lived a somewhat normal life, her parents refuse to accept the offers for treatment and instead encourage her to partake in violent behaviours to "train" her to become a Victor of the Hunger Games.
Most parents would be terrified of their offspring displaying such violent tendencies and incredible unstable behaviour.
Victor and Princess, along with the rest of the Courts, encouraged it and applauded every single meltdown or incident. Their idea, of course, was to make Mascara as absolutely destructive as she could possibly be. The more vicious and sadistic the girl was able to be, the more likely she would emerge as a victor once she entered the arena.
All letters about Mascara's psychosis and various other ailments were burnt and any medication that happened to be mailed to the manor in an attempt to help the young psychopath — or save the rest of One from her, either was fine — were swiftly disposed of.
- Star Trek: The Original Series fanfic Plague Ship plays with the concept. Several of the infected crew are violent (and come pretty close to killing the heroes), but there are several who are perfectly nonviolent - a doctor who is discovered cowering in a room and has to be coaxed out to safety by Kirk, a confused ensign who is trying to get help and a junior team member who acts more like a cheerful child than anything else.
- Fun and Fancy Free: Donald Duck, in "Mickey and the Beanstalk," shown in the trope picture, having a hunger-induced breakdown and attempting to kill their cow so he, Mickey, and Goofy can eat.
- Scooby-Doo: Camp Scare: In one of the campfire stories, Jerry McCreedy, aka the Woodsman, is said to have been driven insane from head trauma, and he roams the woods with an axe. Of course, McCreedy was already mean before going mad, which would give him an additional reason to become violent after losing his mind.
- In Asylum: Blackout, most of the inmates seem to be non-violent. Unfortunately, the ones who aren't are more than enough to dispatch the skeleton crew of workers.
- Bird Box: Justified by the creatures' influence. Anyone with a history of mental illness, regardless of how harmless they were before, becomes obsessed with making everyone else look at the creatures.
- Jason, the hockey-mask-wearing psycho from the Friday the 13th films. Most slasher movie villains in general are either this or some supernatural thing that's returned for revenge.
- Played with in The Guilty. Iben unwittingly kills her infant son Oliver during a psychotic episode under the belief that she's letting snakes out of his abdomen. However, she displays no aggressive tendencies and is horrified when she realizes what she has done.
- Deconstructed in Housebound. The heroine discovers that her house used to be a halfway home for the mentally ill, but was closed down after one of the residents, a girl named Elizabeth, was murdered. When Elizabeth's ghost appears to be haunting the house, solving her murder becomes the driving question of the story. We're led to believe that the killer was another resident, an Idiot Savant named Eugene who turns out to be still living inside the walls of the house and was ultimately responsible for all the seemingly paranormal happenings, but in the final twist, the real killer is revealed to have been one of the care workers at the house, who couldn't cope with Elizabeth's illness and murdered her out of frustration, and Eugene is actually a Misunderstood Loner with a Heart of Gold.
- Subverted in Joker (2019). At the beginning of the film, Arthur Fleck is living with mental illness, but he's a peaceful man just trying to get by. His illness is not what drives him to violence; instead, he turns violent due to many citizens of Gotham abusing him for no apparent reason (as mentioned above, the mentally ill are often susceptible to physical harm). Furthermore, while he's initially checking in with a social worker and taking medications at the start of the film, he loses access to both due to budget cuts, which exacerbates Arthur's already bad situation. That's just the beginning.
- In Love Actually, Laura Linney's character's brother is in a mental hospital. We only see and hear from him briefly, and it seems he has some kind of paranoid disorder (he thinks the nurses are trying to kill him and wants to hire either the Pope or Jon Bon Jovi to perform an exorcism for him). When she visits him, he hauls off and tries to hit her without warning and for no reason. A hospital worker rushes in to stop him and then he's fine again.
- In Miracle on 34th Street, Doris worries that because Kris Kringle believes he's Santa Claus, he'll eventually become violent. Subverted, in that not only is he harmless, well...
- Ms. 45: After she's raped twice in the same day, Thana understandably has a mental breakdown, first killing men she finds threatening, later just men period.
- In On Dangerous Ground, Danny Marlden is mentally unstable; therefore, he kills on any given whim.
- Played for Laughs in The Pink Panther series, especially the later entries as Chief Inspector Dreyfus finds himself getting so irritated with Inspector Clouseau's general foolishness that he turns to increasingly violent reactions to him.
- Princess Cyd: Cyd's brother had an unspecified mental illness. He killed their mother and then himself following an intense argument.
- Psycho: Norman Bates seems harmlessly socially awkward at first, but he is gradually revealed to be a dissociating murderer.
- Rituals: Matthew Crowley is a disfigured World War II veteran driven insane by brain damage he sustained during the war, which has made him violent and dangerous to be around.
- The Ruling Class: Subverted in the first half of the film with Jack Gurney, who downplays the disturbing implications of insanity and is the kind of funny, harmless madman who wouldn't hurt a fly and who is victimised by his own family. In the second half it is their violent assault on his happy world that turns him into a maniac as violent as he is demented.
- Jack Torrence goes violently, and effectively, insane via cabin fever and alcoholism in The Shining, hunting down his terrified family with an axe. This is somewhat justified in the Stephen King novel, as being insane puts him under the hotel's control; that might also be true in the movie, though Stanley Kubrick deliberately leaves it vague. In the TV miniseries remake Stephen King's The Shining, Jack (played by Steven Weber) is more clearly a nasty person only when he's drunk, an aspect King felt Kubrick's film lacked (in Nicholson's portrayal, Jack seems a bit scary even before he falls off the wagon). Problem is, Weber isn't nearly as frightening. As Kubrick said, when some of his actors complained he was pushing them into unrealistic, over-the-top performances: "Real is good. Interesting is better."
- The Silence of the Lambs: Hannibal Lecter. Jame Gumb. Frances Dolarhyde. Jacob Garrett Hobbes. Then again, when part of the premise of a series is that it's about catching serial killers...
- In Split, Kevin is a man with 23 alternate personalities, 20 of whom are perfectly harmless. Unfortunately, the plot kicks off when the three that are an actual danger to others manage to seize control. It's then taken much further when these three succeed in creating a 24th personality, "The Beast".
- The Jackal in Thir13en Ghosts is a terrifying vision of a man in a straight jacket and head cage, a ghost that screams as it approaches people. Played straight and then subverted. The bonus features on the DVD reveal he was a rapist, but deathly afraid of fulfilling this trope again, committing himself to a Bedlam House and willfully choosing to stay there when it burned down, dying in the fire. All of his visible wounds are self-inflicted.
- The Voices: Jerry at first just suffers auditory and visual hallucinations. However, once one hallucination starts telling him to kill, he becomes a serial killer. However, he struggles against this aspect of his mind and hates himself after giving in.
- Voyage of the Rock Aliens has two escaped mental patients, Chainsaw and Breather, who go on a killing spree, with no apparent motive.
- Jake in 11/22/63 apparently believes this. He is certain that Johnny is a danger to Sadie's life, even though he just seems to suffer from some kind of obsessive-compulsive disorder that, while it certainly makes him behave like an emotionally abusive Jerkass, should not immediately translate into being homicidal. He turns out to be right, mind you. He also refers to Oswald as one of "the crazies," who he seems to consider violent per definition.
- After Dark, My Sweet: Escaped mental patient William "Collie" Collins is generally docile and polite when left to his own devices, but he'll lash out violently whenever he thinks he's being insulted.
- After the main character of The Chronicles of Professor Jack Baling goes crazy trying to unlock the secrets of his student's perpetual motion machine, he ends up building a death ray. Violence ensues.
- In Everybody Loves Large Chests every character who is written to be mentally unstable tends to kill everyone in sight once they have the opportunity.
- Harry Potter:
- Bellatrix Lestrange, Voldemort, and the Gaunts are all utterly insane, presumably from inbreeding. All of them (Merope excluded) openly attack people for reasons including amusement. In a subversion, Order of the Phoenix shows us Alice Longbottom, who is so insane that she can't recognize her own son, but just stands around, smiling weakly and handing out bubblegum wrappers. There's also Lockhart, who is pretty much treated like an overexcited child.
- The subversional ones are actually truer to life; the spoilered example is sedate, but utterly detached from reality, and occasionally wanders a bit. Lockhart doesn't just get treated like an overexcited child, he behaves like one as well; he's aware that he seems to be incredibly famous but has no idea why, and the whole thing is an exciting mystery to him.
- Peeta in Mockingjay when he is Brainwashed and Crazy. The first thing he does when he sees Katniss is try to strangle her. It is justified in that the brainwashing was specifically done to turn him against Katniss and make him want to do violent things to her.
- Discussed in the Hurog duology. Ward notes that his Obfuscating Stupidity, which involved talking in a loud voice and slapping people on the back with a bit too much strength, frightened his brother. In an aversion, Ward's mother, a drug addict and Cloud Cuckoolander, is completely harmless.
- Mr Rochester's wife Bertha in Jane Eyre often snuck out from her room and tried to kill Mr Rochester a few times. She even bit and stabbed her visiting brother. And it culminated when she tried to set Jane's room on fire (not knowing Jane had run away two months earlier), leading to the whole house burning down and her own Karmic Death.
- Invoked in Carry On, Jeeves — Sir Roderick Glossop, who thinks Bertie is insane, expresses his fear that the next stage may be "homicidal". (In truth, Bertie isn't what you'd call mentally balanced, but he's far from violent.)
- Mitch Tobin: Both played straight and subverted with the various kinds of mental patients in the third book.
- Discussed in the Modesty Blaise novel I, Lucifer. The man called "Lucifer" is psychotic in the strict sense, afflicted with frequent hallucinations and a delusional belief system, but is amiable and not at all inclined to violence. When Stephen says of the villains that they're "as mad as Lucifer", Modesty tells him sharply that unlike Lucifer they have no trouble distinguishing what's real or telling right action from wrong action; they've made a deliberate choice to be harmful.
- All of the insane asylum residents in Kathryn Hulme's The Nun's Story embody this trope to some degree. The Archangel Gabriel attempts to rape Sister Luke, and another inmate, who is never caught, murders one of the nuns. Even the Abbess (who, much to Sister Luke's surprise, turns out to have been an actual abbess), turns violent when thwarted. It is implied that this is a special asylum for the dangerously insane.
- Oathbringer (third book of The Stormlight Archive): Averted with the Fused, who are exactly the people you would expect to play it straight due to their connection with the local God of Evil. The insane Fused are kinda weird and useless, spending most of their time staring at nothing and giggling. Even their human slaves aren't scared of them. They are still useful in battle, however.
- Swan Song: Does. It. Ever. Alvin Magrim and his fellow escaped mental patients would be right at home in an unrated slasher flick, although some of them merely seem to follow Alvin's lead and shuffle around in confusion after their leaders are killed or injured.
Alvin: (in pure Dissonant Serenity mode) I had a dog named Jesus once. I crucified him, but he didn't come back to life. Before he died, he told me what to do with the people in the brick house. Off went their heads. I fixed the lights here so we'd attract plenty of fresh meat—like you folks. Plenty of play toys. See, everybody left us at [ the asylum]. All the lights went out, and the doctors went home. But we found some of them, like Dr. Baylor. And then I baptized my disciples in the blood of Dr. Baylor and sent them out into the world, and the rest of us stayed here.
- Invoked, but averted, in To Kill a Mockingbird. Boo Radley isn't violent (and may or may not be insane), but the reader's introduction to him is via a story where he stabbed his father with scissors with no provocation.
- In The Wereling Trilogy, Mercy is a complete psycho who is violent by werewolf standards. According to Kate, this is because of excessive inbreeding (which is also the only reason that they want Kate to mate with a newly-turned werewolf, to stabilize things). Kate's brother is just as bad. After Tom kills him, Kate shows how he kept the wallets of his victims as trophies.
- In The Wheel of Time series it is stated that any man able to use magic will eventually be turned insane and then they will kill everyone around them. Heck, the world was destroyed by 101 men who saved the world by sealing the Big Bad who then cursed the source of magic, drove them insane, and caused them to rip the world apart in a horrid frenzy of madness and killing.
- It's not so much that they're violent as the fact that they have the power to make their insane delusions a reality. While one male channeler may or may not be a problem, over a hundred of them deciding that peaches are poisonous, or that mountains belong there, or that they're 100% certain a hurricane/earthquake is coming, leads to a lot of death and destruction. We get a perfect example of how it works at the end of A Path of Daggers, where a male channeler snaps and remains quite good-natured... but one of the protagonists keeps having to explain to him that he should not collapse the palace they're standing in so that he can use the stones to build a shelter for her.
- In the Xandri Corelel series, this trope is part of the reason why prenatal genetic modification became common. People blamed autism and mental illness for the increasing number of shootings, so by the time the dust settled, gun control had been implemented and most mental conditions had been eliminated.
- Accused: Stephen is a paranoid schizophrenic. His delusions lead him to stab his stepmother, believing she killed his mother, his dog, and is trying to do his father and brother in as well. Somewhat justified with his condition, as the belief they're being persecuted is more likely to make the person use violence (which like Stephen they may honestly believe is self-defense or defense of others).
- In Being Human, vampires are shown to be the fantasy equivalent to drug addicts, making them go batshit if they don't get any blood. According to Herrik though, all people are that violent and vampires are just beyond any constraints.
- Blindspot: Background on a jewel thief caught when a heist goes south reveals he was diagnosed as "highly intelligent and utterly amoral" (a fancy way of saying "sociopath"). The Navy scooped him up and turned him into a SEAL for black ops (Agent Reade makes a snide remark about "adding honor and duty to that list"), but when he and his unit mustered out they just turned to armed robbery.
- In the Buffy the Vampire Slayer/Angel universe, Faith, after coming out of her coma and going rampaging, is repeatedly referred to as "psychotic", with direct reference to her violence. In fact, however, she shows no signs of delusions: she's on the edge of mental breakdown rather than past that point. When she does tip over, first temporarily while fighting Buffy-in-Faith's-body, then again when fighting Angel, the immediate effect is to make her more violent — but the first time she basically thinks she's beating up herself, and the second time she's trying to provoke Angel into killing her — a stark contrast to the torture, beatings, and attempted murder that mark her behavior when she's lucid! Furthermore, the second breakdown leads directly to her letting Angel help her, and therefore to her redemption.
- Subverted in an episode of The Closer — the father of a disorganized schizophrenic confessed to a murder even he thought his son had committed, when in fact the son had merely discovered the body.
- Averted in Cracked (2013) a show about a team of police officers and psychiatric professionals assigned to deal with crimes involving the mentally ill. While many of the perpetrators are disturbed individuals, there have also been cases where insane people have been witnesses or victims, including a bipolar psychotic who saw a girl he had been trying to help get murdered, and a boy with Tourettes who tried to find assistance for an abandoned baby.
- Averted in Criminal Minds, where Reid points out that the insane are less likely to be violent, but that when they are, it's usually a lot worse than normal violence. Like in "With Friends Like These...". Reid's mother is also schizophrenic and lives full-time in an institution but has never hurt anyone. Of course, it's a shorter list of the number of criminals on Criminal Minds who aren't mentally ill, and as it's almost never pointed out the majority of them are non-violent, this comes off a bit flat to some.
- Defiance: Pilar has an unspecified mental illness. With medication, things were fine. Once its production was disrupted by the door however she had a psychotic break, trying to kill her children, for which Rafe banished her.
- The degree to which the various incarnations of the Master from Doctor Who are portrayed as "insane" has varied over the years, but they're all definitely evil. The first one isn't referred to as "mad" until his fourth story, at which point he cheerfully accepts the descriptor. By contrast, insanity is used as a Freudian Excuse for John Simm's portrayal. The most recent Master, or Mistress, admits she's "bananas", but her madness is not played as either a cause of or an excuse for her villainous deeds.
- Alpha from Dollhouse appears to be this trope — the composite event that gave him a whole host of imprinted personalities made him into an insane genius and also a psychopathic killer. Actually an aversion, as his original personality was already psychopathic before the composite event, and by the time of Epitaph Two has developed a non-insane personality based on all of his component personalities, much like Echo.
- Subverted in the first episode. The serial killer is a mentally unstable man with violent inclinations and an obsession with red-headed women. He was well aware of his problems, however, and went through multiple psychologists in an attempt to control himself. His current psychologist was dosing him with steroids instead of tranquilizers in order to make his problems worse, all to push the man to kill the psychologist's wife so that he could get her fortune without a costly divorce.
- Subverted again in "Tremors". A man walks into the precinct carrying a shotgun and ranting about how he's "the knight" who killed "the queen". Sherlock immediately works out that the man is schizophrenic with a delusion rooted in Middle Ages chivalry and is able to talk him into surrendering the shotgun. The subsequent investigation reveals that "The Queen" is his girlfriend who was actually murdered by her doctor to cover up his questionable treatment of her heart condition. The doctor took advantage of this trope to frame the boyfriend by manipulating him into thinking he shot her.
- River Tam from Firefly is psychotic, violent — and a protagonist. Her violence is directed at the bad guys (and also, for reasons that might have become clear if the series had continued, at anything with a Blue Sun logo). Before the experiments that made her psychotic, she was a normal, nonviolent (if extremely gifted) young girl. An example of a Justified Trope, since the aim of the experiments was to create a Super Soldier, and violence kind of comes with the package.
- Also justified because they removed bits of her brain, including one part that was supposed to let her push things that upset or bothered her out of mind. So basically she's a psychic supersoldier who is totally incapable of ignoring something that causes her distress.
- The Reavers are also a trope. "Bushwhacked" gives us the descent of someone exposed to their brand of madness (revealed in the movie to be the Pax they were exposed to, which subverts the trope some 99% of the time where Insane Equals So Apathetic You Dehydrate To Death Because You Just Don't Feel Like Getting A Drink Of Water).
- Flesh and Bone: At first Romeo seems a little delusional, but otherwise harmless and kind. In the last episode, he becomes convinced that Bryan is a "dragon" he has to slay and does so.
- Himmelsdalen: Subverted. Although all of the patients are dangerous sociopaths who have been sentenced to life for crimes in various countries, it's mentioned that even those with their condition are not always so. Many only commit nonviolent crimes, with captains of industry and politicians specifically mentioned to often be sociopaths.
- Homicide: Life on the Street:
- The killers in "A Many Splendored Thing" and "Subway" are mentally ill. They're treated fairly sympathetically, and the former even turns himself in out of guilt.
- Zig-Zagged with Pamela Wilgis, the White Gloves Killer. She claims to have at least eight different split personalities, but there's hints that she's faking it to get a lighter sentence. However, her final conversation with Pembleton shows that there's definitely something wrong with her, split personalities or no.
- Horace and Pete: A surprisingly realistic version. Pete has some sort of disorder that causes psychosis, and this occasionally makes him act out violently, but this is always due to Pete being terrified by his hallucinations and panicking. Everyone (except Uncle Pete, and Sylvie to an extent) avoids holding it against him and make efforts to calm him down when he is like this. Any blame for his uncontrollable actions go directly to his insurance and pharmacy for not putting an effort into keeping him out of the hospital, especially when they discontinue the medication without offering a replacement for him.. The revelation that Pete has no choice in this matter makes him break down sobbing, for obvious reasons.
- I, Claudius manages to subvert this despite featuring the actual Caligula. His violent/psychopathic tendencies are explicitly shown NOT to follow from his psychotic delusions: he's a killer from childhood but doesn't go mad until after he becomes Emperor years later. Livia and other murderous characters are described as "mad" by other characters but are not shown as irrational — even Nero, explicitly called "as mad as... Caligula", is clearly nothing of the kind.
- JAG: Averted in "The Martin Baker Fan Cub", where only one of the four escaped mental patients from a VA hospital exhibits violent behavior (by grabbing a sidearm from a police officer) and two others are completely harmless with the mental acuity of small children.
- Discussed and deconstructed by John Oliver on Last Week Tonight with John Oliver. Mental illness is shown to be such an uncomfortable topic in the US that one of the only times people appear willing to talk about it is in the aftermath of mass shootings, and even then, it comes off as an insincere diversion, as ultimately neither problem is resolved.
- Misfits: Zig-Zagging Trope. Lucy, a psychiatric patient Simon knew from his time in an institution, tries to murder them after mockery from the others and Simon ignoring her. However, he isn't shown as violent in spite of his own mental health issues (or no more than anyone else), nor do the other mental patients we see act this way. It may also be a case of her power allowing Lucy to strike out with more impunity than otherwise that leads to this.
- Murder, She Wrote: In "Shear Madness", George got declared insane and sent to a mental hospital after apparently murdering Ann's first groom, and when Bill Sanders dies under similar circumstances, he once again becomes the primary suspect. However, George turns out to be neither insane nor violent.
- The Practice: Mentally ill people are invariably violent, mostly killers on the show. It's justified as otherwise they wouldn't be facing criminal charges that the firm defends them from.
- In Six Feet Under, the one character who is bipolar is also psychopathic and tries to carve off the tattoo on his sister's back, after slicing off his own.
- Insanity in Star Trek-land seems to consist of attacking people, yelling, having bulging eyes, and sweating a lot. And being played by Morgan Woodward.
- Partly justified in the two episodes of TOS featuring asylums — both times they were specified to be for the criminally insane, explaining why these insane people would skew violent even if the overwhelming majority don't. The Tantalus penal colony is for those deemed curable, Elba II is intended for the incurable (by modern Federation science), and dialogue implies it to be the only such installation in the Federation. It has eight patients.
- Actually, it is subverted more often than played straight in cases that don't involve asylums for the criminally insane. Most insane characters are dangerous, but not necessarily violent.
- In "City on the Edge of Forever" McCoy does act violent, but it is mentioned that the cordrazine overdose that sent him into the breakdown induced severe paranoia - which could, in Real Life, lead to violent behavior. Besides, all the violence he does use is focused on escaping these perceived enemies. Once he lands in the past, he's more confused and scared than violent.
- In "Is There in Truth No Beauty?", Marvick, who goes insane after seeing Ambassador Kollos, lands the crew in serious trouble, but not because he's violent - because he's delusional, and managed to send the ship right out of the known galaxy in his terrified escape attempt. Spock, in his temporary bout of insanity due to the same cause, is violent, but then again, Vulcans have been mentioned to have a serious predisposition towards violence which led them to eschew all emotions to avoid destroying themselves.
- Played straight with Castiel after he absorbs 50,000 souls from Purgatory in order to become powerful enough to defeat Raphael. He was always a soldier willing to kill to achieve his goals, but in this case, he goes completely off the rails and kills thousands of his fellow angels when they won't accept him as the new God.
- Inverted with Castiel after he absorbs Sam's memories from Hell. The former angelic soldier becomes a Cloud Cuckoolander and pacifist, refusing to make himself useful during the fight against the Leviathans.
- Played with with Marin, the girl Sam befriends in a mental hospital. Everyone assumes she's violent and crazy, but Sam realizes she's being haunted by the ghost of her brother and he's the violent one.
- Happens to certain ghosts when they become angry spirits. Bobby fears becoming this and thus asks the Winchesters to put his soul to rest.
- There's quite a few characters in Oz that fall under this.
- Subverted by Beecher after he goes insane. He becomes feared within the prison for his viciousness, but he only ever is violent in self-defense.
- Played straight by Adebisi, who is clearly unhinged and gleefully violent for the sake of it at times.
- The Twilight Zone (1985): In "Need to Know", Mrs. Hotchkiss has gone insane after learning the meaning of life from her husband. When the government agent Edward Sayers is questioning her, she tries to attack him with the knife that she had been calmly using to cut a cake a moment earlier. Edward is stunned but manages to fight her off.
- The X-Files:
- "Grotesque" has a Serial Killer who claims that he's possessed by some dark spirit. Scully thinks he suffers from a dissociative disorder and Mulder informs us that he spent the better part of his twenties in a mental institution. The episode deals with the issue of spirit possession versus insanity.
- In "Chimera", the monster-of-the-week is revealed to have got some kind of dissociative multiple personality disorder: split personality. The woman's overt self was not aware that it was her who was committing the murders.
- Zig-Zagged in the video for Poets of the Fall's "Lift." Evidence from his psych hearing combined with imagery from his Happy Place suggests Mad Dreamer Mark, diagnosed with schizophrenia, delusional parasitosis and dissociative identity disorder, is genuinely Ax-Crazy. But in his more stable moments, it takes very little trolling on his part to provoke varying degrees of violent responses from frustrated staff, whether the psychologists are breaking pencils and scattering papers in rage, or a guard is attempting assault.
- Violent J of the Insane Clown Posse is Exactly What It Says on the Tin.
- Implied in The Weight by The Band, with the character of Crazy Chester, who cuts the singer in the fog for no reason.
- Wendigo Psychosis, an (almost certainly) fictional mental disorder from Algonquian mythology that causes the sufferer to try to eat people. It has no cure and can affect anyone at any time.
- Sick Sad World: Subverted. When talking about the Sandy Hook shooter, Dev and Jasmine note that his mental illness alone didn’t account for the murders he committed.
- Many of the more violent wrestlers in the WWE, Face or Heel clearly have some kind of mental problem.
- Randy Orton displays sociopathic tendencies and claims to hear voices on occasion.
- Cody Rhodes is often emotionally unstable, has suffered several mental breakdowns, and may have some form of dissociative identity disorder. His brother Goldust may be crazy or just weird.
- Mick Foley has multiple personalities, all of which display their own individual mental illnesses or abnormalities.
- Dean Ambrose acts like a crazed animal.
- Boogeyman was completely delusional and Lost in Character.
- Al Snow talked to a mannequin head.
- The Undertaker during the Ministry of Darkness angle which is widely considered to be his most evil & violent period. Mark, aka Mark Calaway, (Kayfabe) became lost in The Undertaker gimmick and genuinely believed he was The Lord of Darkness. Vince then points out that not only is he believing, but he has others believing as well.
- Bray Wyatt initially was just a possibly-demonically-possessed, ax-crazy, backwoods cult leader who spoke in dark, cryptic riddles and preached sermons about death and destruction on a nearly weekly basis. As the Fiend, he is a Monster Clown who is even more sadistic.
- Cyberpunk 2013/2020 has "Cyberpsychosis" which happens when an already unstable mind becomes even more unstable with too many cybernetics. In-game, each piece of cybernetics reduces your "Empathy" stat (similar to Shadowrun's "Essence" stat) and with each loss of Empathy, the Player Character becomes more distant to people and start to relate more to machines until every little interaction with a living person can drive them over the Edge and become murderous sociopaths that need to be taken away by the local Psycho Squad to under-go mandatory therapy. With each session of therapy, the Player Character gains two points of Empathy.
- Dungeons and Dragons 3.5 features several spells that can cause the target to become insane. An insane person has to roll on a chart to see what their character does; there is a 10% chance the character acts normally, a 20% chance to run away as quickly as possible, etc. The highest probability action (30% chance) is that the character attacks the nearest creature, friend or foe.
- Also the spell Call Forth the Beast in the Heroes of Horror book. The next time the target goes to sleep, they immediately wake up with a bloodthirsty, psychotic attitude with the sole goal of as much violence and bloodshed as possible. After the spell wears off they fall back asleep and wake up with no memory of what happened.
- In 4E, there is a whole host of powers that force your enemies to attack each other; most have "madness" or some synonym thereof right in the title.
- The Marauders from Mage: The Ascension are Mages who went insane via mundane or magical means. In this setting, how a Mage perceives the world and believes how it should work is what changes reality. With hallucination and delusion, this becomes... somewhat skewed. The Marauders' existence itself is violence upon reality.
- Space 1889 played straight the vast majority of NPCs with the motivation “insane” are violent and hostile to the player characters.
- Warhammer and Warhammer 40,000: pretty much anyone corrupted by Chaos. And seeing as the Blood God Khorne is the incarnation of rage... Then again, it could be argued that everyone in this universe is insane and violent to varying degrees.
- Inverted by the Necron lord Nemesor Zahndrekh. Zahndrekh was driven insane by the reanimation process and so still believes he's a living, flesh and blood being, still fighting the inter-dynasty wars of his youth. However, he's less violent for it, as he still believes in old articles of war such as taking prisoners. His long-suffering bodyguard Oberyn (who is perfectly sane and undeluded) is the one who kills these prisoners before regretfully informing his boss that the prisoners were killed while trying to escape. Again.
- Vezon from BIONICLE basically has new mental disorders as the plot demands, among them a rather literal case of Chronic Backstabbing Disorder. However, he's considered relatively harmless, as he has no powers and is physically weaker than most of the other characters. His violent tendencies are usually Played for Laughs.
- In Poets of the Fall's "The Happy Song," the Villain Song for Mr. Scratch of Alan Wake's American Nightmare, this is the opinion of the Ax-Crazy singer as he smugly admonishes the listener for failing to realize that referring to himself as a "psycho" was Not Hyperbole.
- In American McGee's Alice, the whole plot of the game is about violently abusing and protecting yourself from the mutated enemies seen as mere small cartoons in the book.
- The second game is an aversion. Alice is violent in her fantasies but almost completely helpless in real life. The only time she actually hurts someone in the real world is when she pushes Bumby into the path of an oncoming train at the very end of the game which, chances are, the player would too if they could.
- Splicers from BioShock are all insane and violent, but they have some excuses, such as still believing there is a war on, addiction to ADAM, and being mentally influenced by the Big Bads. This is disturbingly averted in BioShock 2 where the player can find some splicers who do not attack and just sit there, rocking back and forth.
- Yuuki Terumi. though he can come across as quite affable and contained in his Hazama guise, can also completely lose his shit at the drop of a hat. It also slips into gameplay; while he's in his Hazama guise, his fighting style most of all looks like Michael Jackson-ish dance moves and, for some fridge brilliant characterization integration, revolves around baiting the opponent into making mistakes, perfectly fitting his Manipulative Bastard tendencies. When he lets loose for real, though, his fighting-style switches to sheer Sadistic Video Game Cruelty Potential with few defensive options but some of the highest damage outputs in the game when on the offensive. Come the fourth game in the series, it's revealed that he's actually Takehaya Susanoo no Mikoto, Jerkass God extraordinaire, and though he lays off the Maniacal Laughing madness for a while, his ultimate goal of usurping the Master Unit: Amaterasu and turning reality into a cesspool of terror and despair where everyone kills each other on loop reveals that he's way more insane than previously believed.
- The Yukianesa has had a detrimental effect on Jin Kisaragi's mental health, which manifests in his murderous and psychotic rage that pops up whenever he's near Ragna or Noel, As Jin overcomes the weapon's influence across the series, he also acts noticeably less violent and psychotic and is able to better function in battle.
- The Borderlands series's iconic psychos, of course. The sequel also has the Crazed Marauders, although it's arguable whether this counts as the regular Marauders are violent enough without being insane.
- In Dark Souls, any being too heavily afflicted by the titular Dark Soul will inevitably devolve into a raging, psychopathic beast that attacks anything that looks at them funny (and many things that don't). Dark Souls III explains why in its The Ringed City DLC; Gwyn's fear of the Dark Soul and those that can wield its power led him to craft the Darksign as a brand that would cut off humanity's access to their dark souls and the Abyss. Over time they lost the ability to properly control the dark as they were meant to, leading to its two manifestations seen in the series proper; either as the Undead Curse or as a Super Mode that confers great power but completely destroys the mind and soul of whoever is afflicted by it.
- Many of the bosses in the game Dead Rising are mall workers whose cheese slid off their collective cracker during a Zombie Apocalypse. The violence is justified, as those whose reaction tended more towards rocking quietly in a corner were probably turned into hamburger very quickly.
- Discussed and defied in Devotion. Mei Shin has an anxiety disorder, but it is clear to the viewer that she's a scared little girl who both needs and wants help. However, Feng Yu becomes enraged (due to the social stigma associated with mental illness at the time) when a hospital suggests that Mei Shin sees a psychiatrist because his daughter is "not a lunatic". His ignorance towards Mei Shin's condition turns out to have disastrous consequences.
- Dragon Age:
- Played with. The Qunari teach that without the stabilizing influence of the Qun (their religion), their people will invariably go insane and start murdering indiscriminately. People who have left the Qun are called "Tal'Vashoth," and they are almost exclusively some of the worst bandits and murderers anyone has ever heard of. However, it's strongly implied that there's a lot of Self-Fulfilling Prophecy going on; Qunari soldiers are never taught how to do anything but fight, so if they leave the Qun they have no choice but to turn to banditry or mercenary work to survive. And since they've been told that people like them are all insane murderers who will be killed on sight, they have no reason to keep their violent instincts under control. Qunari from other castes are able to live perfectly peaceful lives when they leave the Qun, but the Qunari don't mention them because they don't fit the narrative.
- Played depressingly straight in II with the case of Kelder Vanard. By all accounts, he's a gentle soul, but he also hears demons (probably auditory hallucinations and not actual demons) in his head telling him to kill elven children for the crime of being too perfect. Kelder can't stop himself no matter how hard he tries, and Thedas has no treatment for his mental illness. The only real solution is to Mercy Kill Kelder like he begs once you catch up to him.
- Averted in Dwarf Fortress: Crazy Dwarves might go berserk and attack other dwarves and kill people, but they're just as likely to be Driven to Suicide or strip off their clothes and run around naked. The players, however...
- Averted with Edna & Harvey: The Breakout: the patients at the asylum are perfectly harmless except for Edna and the Keymaster.
- The Elder Scrolls series' backstory has Emperor Pelagius the Mad. Living up to his nickname, he was both utterly insane and, especially later in his life, prone to outbursts of Ax-Crazy violence due to his insanity. After his madness became too publicly apparent, he was institutionalized and died only a few years later.
- The Mad God Sheogorath can go from friendly and helpful to savage and murderous mid-sentence. In one of his myths he "helped" a woman commenting on the beauty of bird songs by gifting humanity with music... by killing her and using instruments made from her body. His plane of Oblivion, shown in the Shivering Isles DLC for Oblivion mostly averts this though. While all of the inhabitants of the Shivering Isles are completely insane, it's mostly in ways that are either harmless or only really harmful to themselves, with only a handful being a real danger to anyone. And while Sheo himself will threaten you quite luridly, the only way to get him to actually act on any of it is to attack him, which will cause him to calmly get up and kill you by teleporting you high above the ground and letting you fall.
- Count Waltz of Eternal Sonata tries to cause this by making the madness-inducing cure-all mineral powder relatively affordable. Because the madness only sets in after a period of time with the normal powder, most people don't make the connection. And in the meantime, you start being able to use magic. Waltz's motivation for doing this is to turn the population into insane magic-users because those make good soldiers.
- Though there are others who you never fight, such as the guy who just walks in a straight line, forever.
- Kefka Palazzo from Final Fantasy VI. It says a lot about a character when his madness makes him The Dreaded on both the protagonists' side of the conflicts and the villains'. An NPC in Final Fantasy VI states that Kefka is a Psycho Prototype, having lost his mind after receiving the empire's first experimental Magitek Infusion, and in Dissidia Final Fantasy it's implied that the process has made him unable to feel anything at all, except for when he is giving in to his destructive urges.
- An apparent invocation of this trope saw a British psychiatric charity condemn Manhunt 2, despite the lead character — and most of the enemy characters — not actually being insane at all. The Japanese release of Dementium: The Ward was met similarly.
- Mass Effect:
- Renegade Shepard can use this trope to justify punching a guy in the face in Mass Effect. He keeps spouting doomsday prophecies, and, well:
Shepard: Say goodnight, Manuel.
Doctor: What are you doing?!
Kaidan: That may have been a little extreme, Commander.
Shepard: It was only a matter of time before he did something crazy. And dangerous.
- A sidequest in Mass Effect: Andromeda provides a handwave for why so many supposedly well-screened Andromeda Initiative colonists and employees have gone rogue: it seems an unforeseen side effect of cryogenic suspension caused a neurochemical imbalance in some individuals that makes them more prone to violence. Doctor Lexi develops a drug regimen to counteract it.
- Renegade Shepard can use this trope to justify punching a guy in the face in Mass Effect. He keeps spouting doomsday prophecies, and, well:
- Neverending Nightmares has the patients in the "Insanity" segment of the game, who will literally rip Thomas's throat out with their teeth if he gets too close or they hear him walking around. Justified as the patients appear to have been horribly abused: they're bruised and battered, lobotomized, bound in straitjackets, and have had their eyes sewn shut.
- Outlast zig-zags and deconstructs the trope. Mount Massive is meant to be an asylum for insane criminals, but out of the many, many inmates you find throughout the game, surprisingly few are hostile, and among those, some only are so because Murkoff denied them or even went against their treatment in order to use them further in Project WALRIDER.
- James Marcus of Resident Evil 0 is driven insane by his death (and subsequent rebirth via virally-infected leeches) which turns him from a relatively mild-mannered scientist into a revenge-fueled monster who slaughters an entire train full of workers — and then a training facility — and he's implied to have released the T-Virus in the first game, which leads to an entire city being NUKED.
- Gregory AKA the Stray Dog in Rule of Rose fell into depression after his son's death. He ended up kidnapping other children as replacements and killing them when they didn't perform adequately, and stalking the countryside on all fours like a mad dog.
- Subversion in Scribblenauts. Entering the word "Psycho" spawns a girl with a knife, but like any neutral NPC, she only attacks when frightened and holding a weapon.
- Team Fortress 2: In "Meet the Pyro", the other classes talk about how scary they are, cut with images of them causing horrible destruction. However, when we see the Pyro's view, it turns out they see the world as a colorful wonderland where they're bringing candy and happiness to the other classes. Of course, the real-world effects of the Pyro's insanity are the same.
- Many characters in the Twisted Metal franchise. Especially in Black where the entire cast has been broken out of an asylum and allowed to fight each other for the right to have their wish come true. This usually involves murder of some kind.
- Warframe: The original warframes were driven insane by the conversion process, leaving them as little more than violent, mindless animals completely unsuited to acting as soldiers. Of course, it didn't help that the Orokin tried to solve this problem by torturing them more and then wondering why that didn't work. Eventually the Orokin had the Zariman Ten-Zero survivors, a group of children with strange Void powers, try. The Orokin assumed that the children would use their powers to break the warframes, but instead they simply showed them basic empathy and compassion, which calmed them down. Together, the children and the warframes became the Tenno.
- Xenogears has some examples.
- Played straight: Id, as Fei is explicitly referenced as having the condition and Id explicitly stated to be an alter.
- Played straight: Anyone under the influence of ''Drive'' in the storyline (though not in gameplay) will become violently insane. Elly and an early game antagonist have this happen in-story (with said antagonist trying to kill children in his path), and it's implied Sigurd was a test subject for the drug in his backstory.
- Implied: Kahran Ramsus/Carlin Ramses appears to be driven to excessive levels of violence by abandonment and combat trauma and borderline personality traits, although, unlike Fei, he does not have a canonical in-text diagnosis.
- Implied: Krelian/Karellen appears to be driven by the desire to force Sophia/Elly to have a relationship with him, then on losing her Sophia incarnation in war, to Gray Goo the entire last remnants of humanity on the planet and become one with "god," as a result of what can be interpreted as extreme narcissism.
- Zeno Clash has a Double Subversion. Ghat notes that the Corwids aren't necessarily dangerous, because they just do whatever they want. Then they decided that what they want to do is attack Ghat, and possibly eat him.
- AI: The Somnium Files plays with this trope in regards to its main villain, but ultimately averts it. Saito Sejima was born with a brain disfunction that caused him to receive a rush of dopamine whenever he killed someone, and this was the only instance where his brain would ever release it. To keep chasing the high that killing gave him, he became a Serial Killer. After a series of body swaps, he ends up in a different body while the game's protagonist, Kaname Date, ends up in Saito's body. Date, now having Saito's same brain condition, receives treatment and ends up becoming an outright better person than he was in his original body. Saito continues to seek the high he got from killing people, but finds himself to be miserable as most brains are not wired to make you happy when you kill someone. Instead of trying to find some other outlet to get satisfaction, however, he chooses to keep killing people and get back into his original body so that he can enjoy killing people again. So while Saito's condition was certainly a factor in causing him to become a serial killer, the fact Date is a good person even though he has the exact same condition and the fact that Saito chose to continue being a serial killer even when he no longer had said condition show that he didn't need to become one. Condition aside though, it must be mentioned that Saito isn't exactly "insane" as he is by no means out of touch with reality and there is a clear line of logic to what he does. Furthermore, there is no real-life equivalent of Saito's and Date's condition, in contrast to other characters with neuroses like Mayumi or Iris.
- Danganronpa: Trigger Happy Havoc: Toko Fukawa turns out to have dissociative identity disorder, and naturally their split personality is the sadistic, Laughably Evil serial killer Genocider Syo/Genocide Jack.
- Higurashi: When They Cry is full of this. In the plot's defense, it does try to justify it via Hate Plague, and one of these people — Keiichi — actually does have some violent background before coming into contact with said Hate Plague; he shot at people with a BB gun and accidentally injured a little girl's eye.. Of course, the main symptom of Hinamizawa syndrome is extreme paranoia, and when you think somebody is about to kill you, what do you do?
- Played straight with the mental construct of Kouma Kishima in Kagetsu Tohya, but averted for the most part with the real one. While he is quite non-neurotypical, his violent moments are reserved for situations where most people would be (i.e. watching assassins kill your family, getting shot in the head, etc.)
- When Freeze Man from In Wily's Defense went insane, he started killing people for the fun of it, despite his being a robot and therefore breaking the rules.
- In The Order of the Stick, this was the result when Xykon threw a bouncy ball inscribed with a Symbol of Insanity into the throne room of the Sapphire Guard. Only a few named members were unaffected, and the last survivor from the ensuing bloodbath committed seppuku out of grief. Justified since that's how that particular spell works in D&D.
- Common in the grimdark Tumblr blogs of My Little Pony: Friendship Is Magic, resulting in the likes of Friendly Twilight (complete with her Madness Makeover from the episode "Lesson Zero"), Flutterstalker, Crapplejack, Lil' Miss Rarity, Fractured Loyalty (Rainbow Dash), and of course, Pinkamena Diane Pie.
- Unclear and played in Killerbunnies. In Razelle's case, she suffers from some form of psychosis but she isn't necessarily violent because of that, rather, it could be that she has underlying impulse problems that worsened her mental illness, which she doesn't have any medication or some help for. On that note, she is described to be rather pleasant, even during those fits of delirium.
- Both averted and played straight in Protectors of the Plot Continuum. Most agents are a little crazy, but those who have real-world disorders aren't any more violent than anybody else (which, granted, isn't saying much when it's a PPC agent you're talking about). However, insanity induced by contact with too much horrible fan fiction does occasionally make agents find themselves a flamethrower and start burning things.
- Played straight and averted in Pyrrhic with some of the students. As a part of the experiment, they are forced to kill, but others were already verging on crazy before it. Some, like Tyra, thought that they were vampires, while others like Jackson have begun to disassociate from reality due to what is heavily implied to be Danson messing with his mind. However, Jackson's is treated with respect, due to the circumstances and was perfectly sane before the experiment. Others like Marie play this straight.
- An interesting variation happens with the character of Salad Fingers. Salad Fingers seems to be oblivious of the death of those around him, and those he directly causes seem to be him forgetting or neglecting them. While he is a Nightmare Fuel Station Attendant, it's not stated how much of it is actually intentional. However, he very violently engages in Self-Harm and enjoys it.
- A variation appears in Survival of the Fittest with those who play the game, especially since many are eventually driven insane, if they didn't start out that way. By necessity, "players" are distrustful and hostile towards everyone else, as they aim to be the winner and Sole Survivor, and many attack all other people on sight. Sometimes this verges on Chaotic Stupid behaviour.
- In the Yogscast Minecraft Series, there are the following examples:
- Shadow of Israphel brings us Templar_Enoch. When he was sane, he wasn't violent, although he was incredibly arrogant. After being driven insane (due to brainwashing from the Sentinels, he murders his fellow Templars, realises what he has done, and then tears his body apart. Later, Lewis Brindley and Simon Lane meet the Evil_Honeydew clone duo, who are both insane and have a love for TNT, due to a malfunctioning cloning machine.
- Duncan Jones is revealed to have an evil clone in the form of "Lalnable Hector". He's described as being mentally insane and apparently has a love of butchering testificates.
- Interestingly, this is often subverted in Adventure Time. The three most obviously mentally unstable characters, The Ice King, Lemongrab, and the Tart Toter, aren't evil or violent. The former is a wizard who occasionally will battle Finn, but he isn't any more violent than the sane characters on the show. As for Lemongrab and the Tart Toter, these guys are just mentally unstable — not violent. It's the sane characters, aka Finn, Marceline, etc., who display occasional violent tendencies.
- Averted on Archer. Cheryl does have violent tendencies, but no more so than most of the comparatively sane members of the cast, and her insanity leads to her hurting herself more often than it does to her hurting others. Krieger is even more obviously insane than Cheryl but shows no violent tendencies at all. Downplayed with Barry Dylan, who becomes much more violent after he goes insane, but it is less of the "randomly attack anything in sight" kind of insanity typical of the trope and more of a burning desire to kill Archer specifically.
- Avatar: The Last Airbender: Azula has always had a penchant for violence, but she was most likely to only use it when it was most needed, to dire effect — an apt comparison to the trick for lightningbending. However, when she goes round the bend, her sadism and violence rocket the hell up. But on the realistic side, she gets considerably less effective when insane. It's doubtful the heroes could have defeated her if she'd stayed sane.
- Family Guy: In "The Fat Guy Strangler", Lois' long-lost brother Patrick has spent his life in an insane asylum after walking in on his mother giving Jackie Gleason head when he was younger. Unfortunately, it doesn't seem to have done Patrick any good, as he still has a lingering hatred of fat men that (thanks to Peter pushing his Trauma Button) eventually leads him on a killing spree.
- Played with for the Trickster in Justice League — on the one hand it is indicated that he does violent things because of his mental illness (at least when he doesn't take his medication), but on the other hand he is significantly less violent and more harmless than his comparatively sane Rogue colleagues.
- Kaeloo: Mr. Cat is an insane psychopath who owns a bunch of weapons and attacks people and objects very violently to the slightest annoyance (or even for no reason at all). Stumpy may be an aversion since he is insane, but not violent. If he is being violent, it's probably in a video game or attacking an object, but not a person.
- Averted in Pinky and the Brain. Both of the main characters are heavily implied to be insane, but Pinky is not violent at all, while Brain does often get violent when he's annoyed but never seriously hurts anyone (unless you count unintentionally hurting himself).
- Ren of The Ren & Stimpy Show is sort of an aversion. He's both insane and violent, there's no questioning that. However, he's only violent when he's being normal; when his psychotic tendencies are triggered, he becomes terrifyingly calm and never lays a mere finger on Stimpy. Instead, he gives elaborate To the Pain monologues. "Stimpy's Fan Club" and "Sven Hoek" contain possibly the best examples of that.
- Rocko's Modern Life subverted this when a clearly unhinged mailman with an issue of Psycho Weekly scared all the nearby subway passengers away by making a seemingly threatening comment about becoming disgruntled ever since he was laid off. He then proceeds to take advantage of the cleared-up space by innocently swinging on a subway strap.