->''The moment their arms spun freely in our air, they were doomed -- for Man has earned his right to hold this planet against all comers, by virtue of occasionally producing someone totally batshit insane.''
-->-- AltText, "[[http://xkcd.com/556/ Alternative Energy Revolution]]," ''Webcomic/{{XKCD}}''

This is when the clinically insane person turns out to be TheOnlyOne who has the right stuff to stop the catastrophe or BigBad. It could be his bent perceptions allow him to see things "normal" people can't. Or maybe the bad thing that happened was so completely [[WindmillCrusader out of the realm of possibility]] that [[CrazyPrepared only the total nut job prepared for it]]. Keep in mind, what separates this from SociopathicHero or other crazies is that this character's madness is '''essential to the task'''. If he was not crazy, he could not do it.

This guy put the Crazy in front of [[CrazyPrepared Prepared]] and [[CrazyAwesome Awesome]], but don't confuse him with an IgnoredExpert or TheWormGuy, who are not actually insane, just misunderstood. Not to be mistaken for his padded-cellmate the SociopathicHero, who is a hero ''in spite'' of his anti-social tendencies, not because of them.

When the whole human race is composed of Heroic Madmen, it's HumanityIsInsane. Compare CrazySane, TheCuckoolanderWasRight and PowerBornOfMadness, although this trope doesn't necessarily involve superpowers. See also BlessedWithSuck and DisabilitySuperpower.


* "Radar Man" in ''Anime/ParanoiaAgent'' has been [[GoMadFromTheRevelation driven mad by the revelation]], but his craziness also feeds him the information he needs to fight the menace to reality. [[MindScrew Sort of.]]
* ''Anime/NeonGenesisEvangelion'''s Ikari Shinji certainly qualifies, since it's implied Unit 01's berserk mode is tied to his manic state.

* [[SomethingPerson Crazyman]] from ContinuityComics, whose power is [[ExactlyWhatItSaysOnTheTin being crazy]]. "Crazyman" is recruited by a secret service as the "Plan B" to dangerous "unwinnable" situations. Danny is to the secret service as ''Series/{{Monk}}'' is to the San Francisco Police Department, and comes up with solutions no sane man would come up with. If Film/JamesBond were insane, he'd be Crazyman.
* A ''ComicBook/TheSandman'' story has Delirium in a foul mood, having hidden herself away in her realm and cut off all access. In order to get to her, Dream recruits several mentally ill people, as only their flexible interpretations of reality would allow them to navigate Delirium's home unscathed.

* [[Creator/SamuelLJackson Romulus]] in ''The Caveman's Valentine''. "I have brain typhoons." But he was [[CassandraTruth the only one]] willing to believe ([[DefectiveDetective and try to prove]]) that [[TheCloudCuckooLanderWasRight the murdered guy was murdered]].

* Common joke among Mathematics or Computer Science students and professors involves asking how many people became insane while studying in their departments. The correct answer is zero: [[SelfDeprecation insanity is a prerequisite]].

* ''Literature/{{Redwall}}'': In High Rhulain, the hare Major Cuthbert went insane after his daughter was killed by vermin. He ended up killing a sea monster single handedly.
* In Larry Niven's ''[[Literature/KnownSpace Madness Has Its Place]]'', Jack Strather's megalomania and paranoid schizophrenia make him one of the few men left on Earth with the cojones to actually resist the invading Kzinti.
* ''Literature/{{Blindsight}}'': The main character's severe autism means he's the only one able to [[AwesomeByAnalysis objectively synthesize]] all of the information and determine just what the deal is with the {{Starfish Alien}}s they discover. Of course he's also unable to bond with other people or empathize with them, so...[[BlessedWithSuck downer]].
** The predatory instincts and complete sociopath nature of the ship's captain (who is an actual vampire) also turns out to be vital in second-guessing the otherwise indecipherable behavior of the alien vessel and its inhabitants.
* In C.S. Friedman's ''Literature/ThisAlienShore'', the Guerans (a mutant race descended from humanity) are all insane, which makes them the only ones who can pilot ships [[FasterThanLightTravel through hyperspace]]. In addition, the heroine's multiple personality disorder grants her a secret power that could alter the balance of power throughout known space.
* Creator/{{Jack Vance}}'s short story "The Men Return" featured a world where causality had basically gone out the window. One character was barely surviving, trying to find patterns where there were none. The ones who were crazy before The Event on the other hand were basically gods.
* The eponymous Strange of ''Literature/JonathanStrangeAndMrNorrell'' must drink a bottle of distilled madness (causing him to lose his mind) in order to be able to see and interact with TheFairFolk on their own terms.

* ''Series/SevenDays'': The only person able to pilot the Chronosphere is Frank Parker, inmate at a military insane asylum.

* There's a rule concerning "Insane Insight" in ''TabletopGame/CallOfCthulhu'' that allows a PC going mad to obtain some hint from the GM as to what they're dealing with or the true natures of the cosmos.

* ''Franchise/DeadSpace'': Isaac Clarke has [[spoiler:the blueprints of the Marker]] in his head. This makes him the perfect guy to go about killing the source(s) of the Necromorphs, and allows him to read and decipher Marker texts. It also makes him paranoid, schizophrenic, and he often hallucinates dead people talking to him. Which is pretty par for the course for anyone who's survived close contact with a Marker, to be fair.
* ''VideoGame/{{Portal}}'': Schizophrenic Doug Rattman was completely right in suspecting the operating system was [[AIIsACrapshoot out to kill everyone]] and so was the only survivor of the lab incident.
* ''VideoGame/TheSecretWorld'': Daimon is a firm believer in this, hence his astonishingly eccentric behaviour. As he explains in both dialogue options and cutscenes, he believes that only individuals who are utterly without structure, dignity and sanity can truly succeed in the dark days, and to this end has made himself as loose, adaptable and eccentric as possible. He even compares this to incidents where drunk-drivers somehow manage to survive accidents that would have killed sober motorists, reasoning that their survival is due to having lost all the self-respect that might have made them brittle, instead being malleable enough to walk away unharmed.
* Anghel Higure of ''VisualNovel/HatofulBoyfriend'' is trapped in a delusion that his life is some high-fantasy epic story and those around him are characters in the same. His fantasy stories are, in fact, a perfect metaphor for some of the other characters' personal storylines, including some very dark secrets about them that not even they know, the "spores" he rambles about are probably the [[spoiler: biological superweapon samples the doctor has in the clinic]], and his senses are ''highly'' sharpened by the paranoia of believing himself a fantastical antihero, enabling him to detect threats sooner even if he can't always communicate them.

* ''Webcomic/{{XKCD}}'': [[http://xkcd.com/556/ Don Quixote to the rescue!]]