Sanity Has Advantages

"Will Graham: I thought you might enjoy the challenge. Find out if you're smarter than the person I'm looking for. Hannibal Lecktor: Then, by implication, you think you're smarter than I am, since it was you who caught me. Will Graham: No, I know I'm not smarter than you. Hannibal Lecktor: Then how did you catch me? Will Graham: You had... disadvantages. Hannibal Lecktor: What disadvantages? Will Graham: You're insane."

- Manhunter and again in the Remake, Red Dragon

The Hero (or another important character) is cornered by the Ax Crazy villain, and there's no possible way out, except... this guy is crazy. Sometimes he will simply let the hero go, sometimes make an absurd mistake based on whatever his problem is. Somehow, he never does this to characters without Contractual Immortality.

On those rare occasions when an Ax Crazy villain becomes Bored with Insanity and turns sane again, the new-found sanity may throw our heroes for a loop when they make their plans...

Compare Not Worth Killing and The Blofeld Ploy. Contrast Power Born of Madness, where insanity has its advantages too.

Anime & Manga

 * Cowboy Bebop: Spike is cornered by Nigh Invulnerable Mad Pierrot, but is saved by Mad Pierrot's paralyzing fear of.
 * A so-called "invincible technique" in Ranma ½, the Cat Fist, induces an Unstoppable Rage in its user that boosts speed and reflexes, as well as giving "ki claws" that can cut through just about anything... but since he acts and thinks like a kitten, he can be distracted by toys and games. Even Kuno figured out this weakness within seconds of witnessing the Cat Fist in action. Not only that, it takes considerable time for Ranma's fear to reach the necessary level, which means he (or she, as the case may be) is simply running around, completely open, unable to fight back until it kicks in... a perfect target for anyone who is aware of what's happening and has the skill to capitalize on it. In fact, the only time that the Cat Fist has been an actual advantage in Ranma ½ is the climax of the Phoenix Pill saga, where Ranma uses it to catch Cologne off-guard: most likely, as an Old Master who may well have been one of the people who proclaimed the Nekoken to be Harmful to Minors, she doubted anyone would be stupid enough to teach it in this day and age, nevermind the trainee actually being willing to use that training.
 * It's notable that teaching this technique involves covering the student in fish and throwing them in a hole with a buttload of cats. The book in which Genma found the technique even points out that the technique is effectively useless (because of all the reasons above) and was only included as a historical curiosity. If only Genma'd turned the page and read that part...
 * Not sure about the anime, but in the manga the page with the insanity warning and how useless the Cat Fist is was stuck to another page, keeping Genma from noticing it.
 * Johan on Monster is a frighteningly effective criminal even while insane. If he had been sane enough to not, he probably would have been unstoppable.
 * On the other hand
 * Used a few times in Black Lagoon. Though, it varies. Sawyer the Cleaner is defeated in her first appearance when she drops her Audiovox, causing her to drop into a near-catatonic depression. The Twins are absolutely brutal in combat, but due to their madness and bloodlust have absolutely no grasp of the bigger picture and are led into a trap that Bailailaka even comments a sane person would never have fallen for. On the other hand, when Revy snaps and goes into Whitman Fever mode, she becomes ruthlessly effective.
 * Not exactly "effective", since she's easily distracted by a room full of unarmed, surrendering people, and won't stop until she killed everyone in her path, no matter what. Ruthless, yes, but a waste of ammunition and time while at the same time attracting unneeded attention, which is the reason Dutch calls her out on it.
 * And when Roberta loses it, she's even more unstoppable than before.
 * In Bleach, after Aizen fuses with the Hogyoku, he proclaims A God Am I and throws away all the tactics that had previously served him so well in favor of relying on raw power to crush his enemies. This trope comes into play when

Comic Books

 * Most of Batman's foes have done this at least once. Hell, you could argue it's The Riddler's whole gimmick.
 * Given a little more depth and drama in some comic interpretations that demonstrate Riddler's shtick as an unstoppable compulsion, and all the problems this gives him. Played right, it's a tragically self-destructive compulsion: "You don't understand... I really didn't want to leave you any clues. I really planned never to go back to Arkham Asylum. But I left you a clue anyway. So I... I have to go back there. Because I might need help. I... I might actually be crazy."
 * In fact, in one early story ('60s) the Riddler realises that he simply cannot commit crimes without leaving riddles. He tries to fix himself, but that doesn't work either...
 * In the Batman: The Animated Series episode "Riddler's Reform", The Riddler actually goes straight and makes tons of money by designing puzzles for a toy company and licensing his likeness to market them. However, he just can't stop thinking about matching wits with Batman... so he decides that the only way he'll ever be secure enough in his new life to actually enjoy it is to kill Batman.
 * The Riddler example was sent up by Exterminatus Now, which featured a joke about the Riddler leaving a nonsensical riddle, and three weeks later Batman is still working on it when the TV news reports that the Riddler has stolen the Moon. Here it is.
 * The Riddler is now reformed and working as a private detective. Since Batman is also a detective, Riddler is now matching wits with him legally.
 * And was hired by Nightwing in the Trinity series to look into why items related to Batman, Wonder Woman and Superman were being stolen and who was behind it. The other heroes think he's insane when Nightwing mentions where he obtained the information, but the series showed that the Riddler had an advantage that even Batman didn't: assorted lowlifes and ex-lowlife like the Penguin are willing to talk to him without having to be threatened.
 * Aaaannnddd now he's back to his old game again, following a kind of reverse-nervous breakdown.
 * Subverted in one episode of Batman: The Animated Series where the Joker develops a plan to kill Batman by lowering him into a tank of piranhas, but abandons the idea because piranhas' faces look like frowns rather than smiles. Harley decides to curry the Joker's favor, captures Batman for him and arranges it so Bats would be upside down, so the "frowns" look like smiles to him. The Joker is, of course, furious for being upstaged, but further outraged that she would create a "punchline" that has to be explained. So he lets Batman down and leaves but seconds later decides this is too good a chance to pass up and comes back to just shoot him.
 * It's not Two-Face's fault that he has to let a coin flip make his decisions for him, so that, if you toss a ton of coins in as he flips, he can't make a choice anymore! Honest, it's not!! Naturally, Batman exploits this in an episode of Batman: The Animated Series where he replaces Two-Face's coin with a trick one that always lands on its side.
 * This is further explored in the comic based on the series; Two-Face ends up with a weighted coin and commits a series of good deeds. However, this backfires, as his good acts not only start to get a little darker, but become suicidally dangerous.
 * In DC One Million, it's revealed that a future Batman eventually cured a future Two-Face by convincing him that, coin toss for coin toss, he made more good decisions than bad ones.
 * In his first appearance, Batman slipped him a coin weighed to land on its side and when he said, "Heads I'll let you go, tails I'll kill you" got him to agree to turn himself in and submit to all necessary plastic surgery and psychotherapy. It worked—but meant the end of Two-Face.
 * The one-shot Arkham Asylum: A Serious House on Serious Earth has Arkham therapists trying to treat Two-Face by expanding his mind to the number of possibilities in each action, by replacing the coin with a deck of cards, eventually planning to work him up to the I Ching. This has a downside, as it means that Two-Face literally cannot decide whether or not to go to the bathroom.
 * In Batman Forever, In the Peter David novelization,
 * The Batman villain Cluemaster began as a cheap Riddler imitation, who used non-verbal clues in the same kind of compulsion. The later writers decided to play with the trope a bit, and had the Arkham psychiatrists cure him of his mania. Now, he's a criminal mastermind who doesn't leave any clues behind. "Gee, thanks, Arkham," says Robin.
 * All of the above notwithstanding, the Joker largely benefits from being insane, since it has the advantage of making him completely unpredictable, which is handy when his nemesis' primary skill is being Crazy Prepared.
 * One of the major advantages Spider-Man has over his Rogues Gallery is that most of them are rather crazy and Spider-Man, editorially-mandated Deal with the Devil notwithstanding, isn't. None of them illustrate this better than his Arch Enemy Norman Osborn aka the Green Goblin. Norman is a manipulative sociopath on a good day. The rest of the time he's an Ax Crazy monster in a garish outfit riding a hoverglider throwing pumpkin bombs. No matter how well he manipulates, schemes, and kills his way into power, Osborn always ultimately loses because he's too crazy to keep it together once he reaches the top.
 * In one early Spirou and Fantasio adventure, they have to stop a Mad Scientist from launching a device that will set fire to the Earth's atmosphere. They fail. They say their goodbyes... only to discover that the Mad Scientist was, well, mad and his doomsday device was mostly made out of old shoes.
 * Zot's archenemy, Dekko the cyborg Mad Artist, tends to get beaten by his own self-destructing insanity at least as much as by the hero's actual efforts.

Literature

 * The page quote is a near-exact adaptation of a scene from Red Dragon, although Graham's original explanation is "Passion. And you're insane." Lecter abruptly changes the subject.
 * This is what allows Tavi in Codex Alera to defeat an Ax Crazy but vastly superior opponent. He uses her name and reputation to start psychoanalyzing her in the middle of their Duel to the Death, and watches her reactions to give a Hannibal Lecture that drives her into making a mistake due to screaming, psychotic rage.
 * In Jonathan Strange & Mr Norrell, The Gentleman could have killed the magicians at any time, but as the book explains fairies have a greater capacity for magic, but much less of one for reason. Instead he spends years watching them and coming up with plans to destroy them while doing nothing, under the belief that these plans wouldn't work. And the actions he does eventually take backfire on him in the end.
 * In Brisingr of The Inheritance Cycle, Brom hints to Eragon in a memory that Galbatorix's insanity is something that he should use to his advantage when it finally comes time to face him. "Whatever you do, you must remain nimble in your thinking. Do not become so attached to any one belief that you cannot see past it to another possibility. Galbatorix is mad and therefore unpredictable, but he also has gaps in his reasoning that an ordinary person would not. If you can find those, Eragon, then perhaps you and Saphira can defeat him."
 * In the backstory of the Vorkosigan Saga, Mad Emperor Yuri decided that his relatives were plotting to overthrow him, so he ordered the assassinations of anyone with enough Royal Blood to claim the throne. This meant he ordered the maternal side of Aral Vorkosigan's family assassinated, but since the Vorkoisigan side didn't have a strong claim to the empire, he left them alive. If he'd been sane, it might have occurred to him that Aral's father (Who happened to be the most talented general on the planet) would be upset about his wife and children being brutally murdered. This leads directly to Yuri's overthrow, making his fear a Self-Fulfilling Prophecy.
 * In Harry Potter, it's repeatedly alluded to that Voldemort's egomania is keeping him from being a much more effective villain by compelling him keep the Villain Ball on his person constantly. He starts juggling it in the final book, and becomes much more dangerous.
 * Probably the best example is the horcruxes themselvse. Even Harry and Ron are smart enough to realize that had he made them innocuous items and hid them in plain sight, it would be impossible to find them. Fortunately, as Dumbledore explains, Voldemort's obsessive nature focuses on trophies and rituals, so he needs them to be special items, hidden in special places, which makes them easier to track.
 * Played with in the Poirot book, Lord Edgeware Dies, in which Poirot admits that what he really needs to catch criminals is a sane partner, so he can observe what conclusions the criminal expected a sane man would draw from his misdirection.
 * In The Belgariad the king of Cthol Murgos is mentioned as having been a great warrior once, but by the time he appears his insanity had grown to the point that when he meets his arch enemy in battle he's so focused on killing him that he doesn't bother defending himself. He dies still screaming for the man to come back and fight him.

Live-Action TV
""Are you sure? Does the vomit really HAVE to be first?""
 * The Doctor from Doctor Who has defeated many of his enemies via his intimate knowledge of how the latest Mad Scientist or Omnicidal Maniac will react, having encountered so many of them over the centuries that very little surprises him any more.
 * Special mention should go to the Master, who is probably the reason the Doctor can predict the reactions of the Mad Scientist or Omnicidal Maniac of the week.
 * And Davros, of course.
 * Kamen Rider Ryuki: Asakura Takeshi (Ouja) is raving mad and prone to crazy, suicidal behaviour. Once he starves his bound monsters until they threaten to eat him. Once, after failing to kill a long-running enemy, he charges a bunch of armed policemen without even using his powers.
 * Deadliest Warrior has two according to the experts.
 * Saddam Hussein defeated Pol Pot, despite the fact that both were classified as insane Saddam was still more sane than Pol Pot. They say that, like history shows, Saddam would use his violent insanity to his advantage [killing thousands of Kurds to prevent rebelions and surviving the Iraq/Iran War and Gulf War despite overwelming forces] while Pol Pot's insanity was selfdestructive [the damaging genocide and being easily defeated in the Cambodian–Vietnamese War].
 * Hernan Cortes defeated Ivan. Cortes isn't classified as fully insane, just greedy and violent. Infact, he was able to make good choices to defeat a larger Aztec army and avoid arrest from the Spanish Empire [by bribing the army sent to kill him]. While Ivan is insane from drinking mercury and alcohol constantly and being bipolar. Infact after his reign, the Russian Empire almost collapsed.
 * In a heroic example, Monk's severe OCD makes him the world's greatest detective, but also makes him too unstable to be relied upon in desperate situations, as evidenced by the pilot in which his condition causes him to freak out and let the killer escape. This is why he's not been allowed back on the police force since the Heroic BSOD he had following his wife's death.
 * Even in the depths of the seriousness of the series finale, the OCD comes shining through full force in an intentionally Level Breaker moment after Monk has been poisoned and told he will vomit first, then die. Cue awesome run-on gag of Monk focusing on the vomiting aspect and ignoring death.


 * And to make matters worse, it turns out the final villain of the show took full advantage of the OCD  As a secondary spoiler/example of this trope,   Essentially, all his old OCDs flipped and became the 'positive, happy' versions of his old neuroses.
 * River Tam in Firefly is unbelievably intelligent, combat-capable, and, but her usefulness in a number of situations is clouded by mental instability.
 * When it comes down to it, this is the entire point of Criminal Minds (and similar Real Life organizations): Serial killers are rarely mentally stable. Therefore, they have patterns that can be predicted, flaws that can be exploited, and make mistakes that can be taken advantage of. If the criminals they hunted were actually Genre Savvy, they wouldn't have lasted the first episode.
 * The primary reason House has a team is to balance out his various manias.

Tabletop Games

 * In Unknown Armies all magicians are basically insane, to the point that several of the most powerful NPCs are completely mundane, and players without powers often have significant advantages over those with, and various examples of possible mundane parties are discussed in the Global level of the sourcebook. One of them is even a bunch of stage magicians who pretend to have real powers. In the New Inquisition sourcebook, they explicitly address this trope, pointing out that by virtue of not having any magical powers, the head of the conspiracy is sane, his vision unclouded, and capable of everything a multi-billionaire with few ethical scruples can do. Which is quite a lot.
 * Betrayal at House on the Hill has the Sanity stat, which often determines whether or not your investigator will keep their wits about them... or simply stay alive.
 * Exalted: most antagonists come with some form of insanity-related dysfunction which will lead them to make drastic, exploitably bad decisions. Examples include other Creation-based Exalts, who are usually blinded by the towering hubris of the Great Curse; the Yozis, who come with a heavy paradigm blindfold that leads to them interpreting nearly everything in terms of their own fundamental concepts; apostate Alchemicals, who are compelled by their condition to become less and less stable as time goes on until the killing starts; and ghosts and Deathlords, who naturally default to melodramatic passion plays rather than the organic behaviour of humans. (Should you be coming up against a high-Essence sane Alchemical, who will likely have a decent Clarity rating, you might actually have to invert this trope by making seemingly illogical moves to catch it unawares.)

Videogames

 * Portal: Subverted by the Rat Man. He was a programmer who survived GLaDOS's takeover of Aperture Science by being a paranoid schizophrenic who believed that the computer was evil and planning to kill them all. The reason this is a subversion instead of inversion is that the rest of his team knew that she wanted to kill them all at every boot up but still gave her access to the neurotoxin emitters when she started playing nice. Thus, the crazy guy was the Only Sane Man.
 * In Fate/stay night the Mad Enhancement skill, exclusive to Berserker class Servants, results in a increase of basic parameters but at the cost of mental capacities as well as personal skills.
 * However, the Berserker of Fate/Zero has an ability called Eternal Arms Mastership that allows him to retain those skills. It's exactly as broken as it sounds.

Webcomics

 * In A Miracle of Science, a thorough understanding of Science-Related Memetic Disorder means that Vorstellen Police officers play their role correctly, ensuring a mad scientist will surrender once their illness takes its course.
 * In the "Fire and Rain" arc of Sluggy Freelance, Oasis comes very close to killing Zoe, but suffers a complete Villainous Breakdown and collapses in tears moments before delivering the fatal blow.
 * This 8-Bit Theater strip follows the same vein, as Black Mage reveals that he plans to help Chaos because by his (it's?) very nature he is just as likely to turn the world into cake as he is to destroy it.

Web Originals

 * The SCP Foundation's acquisition of SCP-668 was made significantly easier by the obsessive behavior of the Ax Crazy Serial Killer employing it in his killing spree. If he'd had the sense to move around more, the foundation would've had to resort to nuking the whole area.
 * Inverted with Doctor Steel. "I mean, you can get away with pretty much anything if you're bonkers."

Western Animation
"Darkwing: Fortunately, we have a psychological advantage. Launchpad: Because, uh, we're sane and he's not?"
 * An episode of the Disney Aladdin series featured a (non-villainous, though the heroes did not realize that at the time) reality-altering ("more powerful than a palace full of genies") catlike creature who was the Anthropomorphic Personification of Chaos, who shrunk Jasmine and then changed her back just because nobody was expecting it.
 * One episode of Re Boot, where Hexadecimal had gotten "The Medusa Bug", which was turning everything in Mainframe to virtual stone. Bob (being immune) went and talked to her, mentioning casually how nice and orderly everything would be from now on. Naturally, Hexadecimal was the epitome of chaos, so she immediately undid it.
 * Played with on Darkwing Duck, during Megavolt's introduction in 'Duck Blind'.


 * In the Futurama episode "Insane in the Mainframe", Roberto's hostage situation ends when, convinced that Fry really is a battle-droid, he has a Freak-Out and jumps out the window.
 * Let's face it: How many times would Invader Zim have conquered or annihilated the Earth if he wasn't completely out of his Irken mind?
 * A non-villain example happens to Ben 10: Alien Force's Doctor Who Expy Paradox. He claims to have been driven mad after a thousand years of being woven through the fabric of time and space until, as he says himself, he grew bored with insanity.
 * In Generator Rex, Breach is an incredibly powerful teleporter capable of transporting anyone or anything anywhere with little apparent effort. If she put herself to it, she could be a bigger threat then her boss Van Kleiss. But her insanity and crippling OCD keeps her as a minor villain.
 * In Avatar: The Last Airbender there was an Agni Kai between Zuko and Azula where Zuko intended to take an advantage of his sister's crumbling sanity.
 * Phantom Limb from Venture Brothers spent the third season insane but becomes a true menace again once he regains his sanity and builds the Revenge Society into a true supervillain alliance.

Folklore
"Sam:"
 * Trapped by a vampire? Throw some rice/beads/knotted bits of string at it! They have to stop and count it. Ah ah ah!
 * Beautifully done in The Rashomon episode of The X-Files.
 * And subverted multiple times in Discworld's Carpe Jugulum, where this is one of many traditional vampire weaknesses the Magpyr clan had overcome.
 * Of course, it's inverted right back when, under the stress of having their plan spontaneously collapse when, the Magpyr's conditioning starts to fail. Since the Magpyr's conditioning involved knowing the root cause of every traditional weakness and countering that, the resulting collapse added a form of hypochondria of sorts. So, for example, they're no longer immune to religious symbols... and they've memorized so many that they see religious symbols everywhere.
 * Charby the Vampirate subverts it in one early strip. He is compelled to count a handful of beans his intended victim throws at him, but does it by determining the average weight of a bean, weighing the pile, and extrapolating how many there are from that.
 * Subverted in the sequel to Dracula 2001, when a vampire accurately counts thousands of grains of rice before they even hit the ground.
 * In Supernatural, it's leprechauns that have this problem, not vampires.


 * Likewise, the kappa of Japanese folklore. Its Weaksauce Weakness is that its power is derived from a pool of water carried in a dent in the top of its head. Not only does it have to avoid spilling the water in an attack, but it is also supremely polite: if you bow to it, it will bow back to the same degree as you do. All a human victim has to do is bend over and offer a polite greeting, and the kappa will be obligated to return the salutation, despite the fact that it deliberately spills the water it requires.

Real Life

 * Anyone who thinks that being mentally ill is somehow 'cool' either has never been mentally ill or has a very selective memory.
 * It's likely more that they feel envious of and desire all the attention a mentally ill person receives. Never mind the chance that the person with the illness doesn't want it, but needs it.
 * This is usually caused by the fact that most people know mentally ill characters from books and movies where they are either portrayed as unusually sympathetic or their insanity is offset by some extremely useful skills. In reality, 'mad geniuses' (highly intelligent mental patients, not savants) are geniuses that went mad (some research indicate that very high mental capacity may be linked to the chances of developing dissociative disorders), not madmen who developed superior intellect due to their insanity.
 * World War II might have gone quite different if the Nazi party didn't let its ideology get in the way of practicality. When Hitler invaded the Soviet Union, most of the nations he invaded would have been quite happy to get out from under Soviet rule, and could have provided critical support and reinforcements for the German military. Instead, since they weren't Aryan, they were killed off, which not only lost the Germans potential allies, but encouraged everyone still alive to defend the Soviet Union to fight to the last man.
 * He also might have made sure he finished off his enemy in the rear. He might have further opted not to declare war on the one nation which had the capacity to open up two other major fronts against his armies.
 * Hitler's megalomania aside, he also had a tendency to relieve his most effective field commanders due to him not thinking they were reliable. Things may have gone differently for Army Group South had he let von Manstein remain in command (this guy made Rommel look like a novice and with good reason).