With Great Power Comes Great Insanity

"EPA Official: Sir, I'm afraid you've gone mad with power.

Russ Cargill: Of course I have! You ever tried going mad without power? It's boring! No one listens to you!"

- The Simpsons Movie

It seems like any major military or corporate backed venture to give a mundane person super powers or just enhance their normal abilities always results in the test subject going uncontrollably berserk as a side-effect.

Sometimes the choice of test subject is clearly to blame. Convicted criminals make pretty poor guinea pigs if you're trying to develop a Super Soldier who can punch out a tank, yet nobody in any of these programs ever seems to have been given the most basic psychiatric evaluation. The evidence indicates a connection between morals and one's ability to remain "sane." Normally, using the power makes you crazy the longer you use it, because Evil Feels Good, but a noble, heroic character is better able to stay in control.

Other times, it seems that insanity happens as a side effect for no discernible reason other than to justify the needs of the plot and/or give the super individual a weakness that they must struggle to balance and maintain. This also gives the Badass Normal their one edge over the competition as they lack this weakness.

This trope can also arise if the principle that knowledge is power is extended to Things Man Was Not Meant to Know.

Sometimes, the creators of the super being realize the error while in the prototype phase and will seal the subject away, hoping everyone just forgets about them. This never works. Often, the first subject to undergo the process -- or a single subsequent subject -- will turn out okay, so on top of all the various other issues that the treatment has, it's usually their job to clean up the mess made by subsequent failed attempts. If it's a Science Is Bad story, the sponsors of the program are likely to just keep pumping out nutty prototypes hoping they'll eventually make one that is not insane.

If all else fails, it'll seem like it happened just to make the Aesop "Power tends to corrupt, and absolute power corrupts absolutely" appear in the story. Karmic Death is a frequent end for not only the subject, but the scientists who created him/her/it.

May be either the cause or the result of Science Related Memetic Disorder, especially if the person is already a Mad Scientist to begin with.

HG Wells used the trope in The Invisible Man, making it Older Than Radio. In fact, invisibility seems to drive one insane more than any other power, due to homage. Less well known, Plato had a story about invisibility with the same result. Because invisibility can do things like letting you escape easily without consequences or peek in the girls' dressing room.

Shapeshifting and telepathy are close seconds to invisibility as potential causes of this trope, probably due to Personality Powers; after all, changing identities too often might result in losing track of the real you, and having other peoples' thoughts in your head is a lot like voices in your head, right? Anything can theoretically trigger it, though. Getting energy blasts can result in Psycho Electro. Getting Charles Atlas Superpowers can result in Ax Crazy. Getting Flying Brick powers can result in A God Am I or Beware the Superman. Knowing that one is a Reality Warper will cause the warper to remake the world in his own image. And of course, think of all the Power Perversion Potential.

This is the inverse of Power Born of Madness. Often occurs when someone acquires god-like powers. Always occurs when someone makes serious use of an Artifact of Doom.

A.K.A. Comes Great Insanity for short, to go with the original version, Comes Great Responsibility. Compare The Corruption, Drunk With Power, God for A Day and Mad God.

Anime and Manga

 * During an episode of Magical Project S, Misao dreams about having magic powers and the "fun" she would have using them. When she actually got said powers, she becomes the arguably insane persona of Pixy Misa (who tortures the entire main cast).
 * In Suzumiya Haruhi, the titular character is kept Locked Out of the Loop regarding the fact that her friends are all examples of the very weirdness she seeks to find for this very reason. Already a Jerkass Tsundere, they're afraid that if she discovers that aliens, espers, dimension/time travellers and other such entities are real, she will manage to make the intuitive leap and realise that she is a Reality Warper of such power that she is, in all practical terms, a goddess. Given how much strain she can put on the fabric of reality even while she's unaware of her power, they naturally fear that allowing someone of her attitudes and ethics full control of her abilities would effectively bump her to Eldritch Abomination status.
 * In fact it's implied that this has already happened a number of times, and the current reality is just one of many she has created. The current one was created three years ago, but because she created the reality as though it had always existed, only aliens, time travellers and espers with the ability to sense Haruhi's intense power realised what happened.
 * Cowboy Bebop, "Pierrot le Fou": A government test subject is given superhuman assassin skills, and then goes crazy as a side-effect. Given the methods shown (the fact that no explanation of any sort is given for what, precisely, is being done, it's all the more disturbing), it's not too surprising.
 * In The Big O, Nietzsche Wannabe villain Schwarzwald is the only known character to figure out the big secret. As a result, he goes batshit insane, wraps himself up like a mummy, and spends the rest of the series raving about philosophy, leaving typewriters lying around everywhere he goes, and.
 * Mobile Suit Gundam: A common theme in the franchise, most notably Zeta Gundam and Gundam ZZ where all Newtypes are often mentally unstable in some fashion, may have forms of amnesia, be brainwashed, though in some other cases they're just plain stubborn.
 * Gundam SEED plays on this by giving performance-enhancing drugs and treatments to criminals who are doing it in exchange for a full pardon. Naturally, this drives them to insanity in combat... which is what was planned. As a result, they are given drugs in such doses that by the time combat is over, they are having withdrawal symptoms and are manageable again. Withdrawal will also kill them if they are deprived of the drugs for too long, thus ensuring their loyalty.
 * In Gundam Seed Destiny, Blue Cosmos has been attempting to create "Artificial Coordinators" through depraved combinations of surgery, hypnosis, insane training, drugs and other horrors. Of the dozens of children selected for the project, only a few survived, and those seen in the series are all, understandably, raving mad and almost incapable of functioning normally in life. Without routine "maintenance" their bodies break down and they die. The sad thing is that in comparison to SEED's pre-Extended (see above) they're all poster children for Mental Health Week: Stellar Louissier, i.e, is a sweet if incredibly childish and still very sympathetic young woman who loves to dance, as long as you don't tell her that either she or her friends will die.
 * In Gundam Wing, the ZERO System gives the person who uses it incredible reaction times and tactical predictions bordering on prescience. If he can't focus on the battle, those violent predictions start afflicting whatever he starts thinking about (like say his girlfriend, or that nice peaceful space colony over there), and soon enough he's a psychopath slaughtering whatever the System says is his enemy.
 * Similarly, Gasaraki has mecha pilots who were given a cocktail of boosting drugs in order to improve their battle performance (without their knowledge or consent, and said drugs was actually fluid extracted from the muscles of a 1000 year old demon), and the inevitably go berserk from the effects, before either lapsing into a coma or suffering cardiac arrest.
 * DNA had The Rival become the Big Bad when he gained the power to "absorb other people's DNA". Don't ask how that works or why it gave him a Battle Aura and shapeshifting powers, it just did.
 * Anime classic Akira centers around the results of government experimentation on a Japanese gang member with a serious inferiority complex. As a result, the newly created Big Bad Tetsuo runs amok with his telekinetic powers until he mutates, explodes, and forms either a new universe or... something.
 * Death Note drops some hints that Light Yagami wasn't entirely stable before gaining the power to kill anyone in the world at any time, but his sanity certainly heads downwards after that. In fact, all the Kiras in the series seem to go bonkers after picking up a Death Note, since it seems to take the major flaw in their personality and magnify it -- Light and Takada's narcissism, Mikami's fanatical desire for justice, Misa's obsessiveness and greed.
 * It even says in chapter 19 that "with great power comes great evil," which is pretty darn close, in Light's case.
 * The Dragonball Z movies have Broly, who's more or less the personification of this trope (although it is also heavily implied that the life-threatening experiences of his childhood also contributed quite a bit to his insanity as well).
 * And in DBGT, Goku loses his reason and turns into a giant, supremely powerful golden ape when he first transforms into a SS4. He Got Better.
 * That was simply the latest in a long list of giant ape transformations from Dragonball and early DBZ, which had the same effect: multiplying the Saiyan's power level by a factor of 10, but causing their minds to become animalistic. Vegeta was the only one to remain sane in this form... presumably due to actually being trained in its use.
 * Frieza's reason for using transformations to hide the bulk of his power is heavily implied to be due to losing what little sanity he already had if he went all out.
 * In Bleach, Ichigo's powers are greatly amplified when his inner Hollow is released, but he suppresses it in order to preserve his sanity. Even then, suppressing it didn't work in the long run. It takes a major Battle in The Center of The Mind for him to gain control over it.
 * Aizen has never been entirely sane but his insanity slowly becomes more and more obvious the greater his power becomes.
 * Also, Kouga (from the third anime filler arc) fits this trope perfectly. His power is truly enormous; and he quickly goes insane.
 * Itsuki's Glam Sight in Rental Magica gives him his Crouching Moron Hidden Badass ability that makes him just the right sort of leader for his team of mages. However, the more he uses it, the more it eats away at his sanity. Thus, Honami and the others warn him not to use it as much as possible.
 * Inu-Yasha's heritage of demonic power from his Greater Demon father is so strong that it is too much for his half-human body to handle. That's why his father created the Tessaiga, to serve as a Restraining Bolt on Inuyasha's demonic power and thus preserve his sanity (while also making up for the power surpressed with the sword's own usefulness). If the sword is taken from Inuyasha or broken, he must refrain from getting too emotionally excited, or he risks unleashing his full, uncontrollable strength. Worse, each subsequent overload renders him more insane than the last, and it becomes harder to snap him out of it. If left unchecked, Inuyasha would eventually be reduced to a mindless monster killing and destroying everything and everyone around him, permanently.
 * Contractors in Darker Than Black appear to have 'complete lack of conscience' as one side-effect of gaining their powers (and their powers are usually destructive in nature). Even the sanest amongst them are Affably Evil or Anti Heroic at best and have no problems with taking lives, though whether it is the powers themselves that cause it or the result of the extensive Masquerade surrounding them and how their fellow humans treat them is up to debate.
 * Human-type homunculi of Busou Renkin are a borderline example, as while becoming a homunculus does grant a human great power, none of the ones seen seem like they were particularly sane beforehand. Victor, though, is a dead-on example, as becoming a Victor made him do a Face Heel Turn from an alchemic warrior to a demigod attempting to destroy all alchemy.
 * No, the cause of his Face Heel Turn was.
 * Sensui from Yu Yu Hakusho would probably count, as he seems to have been at least slightly cracked before he officially went insane on the mission to the Black Black Club. (As a child, he says that he is the "warrior for justice". Wondering why demons only attacked you as opposed to other people, and knowing about the extent of your own power to destroy other living things leads to this trope.)
 * A major part of Tsukihime; whenever most characters use more of their potential powers, a direct effect is the deterioration of their sanity. Examples are
 * Arcueid's case is kinda special in that she does not gain additional power during her "blood-lust" mode; she always had that power, "blood-lust" simply makes her no longer hold back. Well, unless she's fighting against Shiki, because only normal women can resist the Nanaya glands.
 * In Type-Moon's same-universe series Fate/Stay Night, the Servant class Berserker has this as a specific class trait - the ability to sacrifice sanity and reason for immense combat power. Also,, whose brokenly powerful magic only came about due to him becoming functionally insane This results in him using his own body to power his magic, allowing him to bypass natural limitations (i.e. survival instincts) that plague "normal" mages - who themselves are dedicated enough to withstand horrific pain for their magecraft - and
 * Shirou loses his mind during one of the dead ends in the "Heaven's Feel" route because he used too much of Archer's power and it corrupted him because they are not completely the same person. Shirou himself is pretty insane already since he tend to push himself beyond his limits because he places little value on his own life. However, this has to do with his way of thinking and little to do directly with his power or rather, his "Reality Marble".
 * In Chrono Crusade Joshua Christopher is given the horns of a demon by the Big Bad. The power is too much for the small boy, however - within minutes he's gone completely insane, using his powers to freeze everyone around him in time and destroy the orphanage he lived in. It gets so bad that later.
 * It's even worse than that in the manga. . That constant, painful noise that Joshua was complaining about?
 * In the anime, though the horns did damage his mind on their own, the "noise" he complained of was the thoughts of every human around him. In other words, uncontrollable telepathy that forced him to hear what every single person around him was thinking, all at once, all the time. No wonder he went mad if he had to be near people.
 * Due to metatron poisoning, Radium of the Zone of the Enders OVA, Idolo, goes completely off the deep end after spending just a moment too long in the cockpit of the Idolo. This does not end well for anyone.
 * The same can be say for Ridley Nohman with his Anubis, from a rather immoral rebel leader (in Dolores, I)into destruction-obsessed guy (ZOE: The 2nd Runner).
 * In Devilman Lady, the entire story centres around evolution and the gaining of vast, beast-like powers by ordinary people, many of whom go insane. The main character, Jun, for much of the series appears to be descending into insanity herself despite her best efforts not to. The climax moment of this aspect of the series is when, having been prevented to indulge her bloodlust by the Human Alliance, she attacks a nurse, but ultimately overcomes her instincts by drawing her own blood.
 * In Tenjho Tenge, characters who possess supernatural powers are remarked as always being in danger of becoming insane. A classic example of this is Natsume Shin, Maya and Aya's elder brother who was overwhelmed by his powers and started killing random people. This leads to powers being referred to as "Dragons" that will devour their wielder's sanity. Because of this, there is a tremendous social stigma attached to the possession of supernatural abilities, which naturally only serves to aggravate the problem even more.
 * S-Cry-ed shows this one off pretty well, with most (if not debatable all) of the Alter Power users being completely insane to some degree. Particular samples include Straight Cougar, most of the one-shot villains and our main Kazuma (whose personality initially flips between Jerk With a Heart of Gold and nice-guy... only for the nice guy to comepltely vanish by the final battle).
 * A few of the characters in the Mai-HiME mangaverse are given special earrings created using SEARRS technology, which allows them to summon more powerful CHILDs than any of the HiME, and they don't need an emotional anchor to use said powers. However, relying on this ability too much can drive them insane.
 * The cyclone-riders in Uzumaki.
 * A Claymore who activates her demonic powers (i.e. "Awakens") gains great power but stands a chance of losing her humanity and turning into a human flesh-craving demon permanently.
 * In Rosario to Vampire being injected with a youkai's blood gives you all of their abilities for a short while. Eventually the effect starts wearing your body down. One time too many will kill you (if you're lucky) or horribly mangle your body and, if vampire blood is involved, leave you a mindless killing machine. Fortunately there are ways to counteract the less-than-desireable effects.
 * Subverted with Tsukune, in the fact that he doesn't even have a mind anymore when this happens.
 * In Get Backers, Ginji and have this as a side effect of their Superpowered Evil Sides. Ginji's "Lightning Lord" aspect is quiet, cold and utterly ruthless, while  They're always sorry afterward.
 * In Soul Eater, the characters infected with Black Blood have their strength increased tremendously when they use it, but also run the risk of losing themselves completely to insanity. Oops.
 * Also the result of mis-using the Nakatsukasa Purpose, which also drives you mad whilst killing you slowly (it damages your soul).
 * This is also the reason why witches are so dangerous in the series. Up till a certain age they're normal. But then the "Sway of Magic" affects them and causes them to be evil and destructive. Though there are a few exceptions where this doesn't happen due to the witch having their mind on something else other then their magic. In addition, those who possess magic which has little in the way of destructive capabilities are much more resistant, if not outright immune to the sway.
 * Several characters use insanity to their advantage, but most do so from outside sources where they are at risk of permenantly losing their minds. Even the Nakatsukasas trace their power back to Arachne's experiments. Kid's is a unique case so far because he is an Anthropomorphic Personfication of a kind of insanity, albeit a deliberately weakened and incomplete one (a 'fragment of Shinigami').
 * In Berserk, the main character finds that he can enter into an Unstoppable Rage like never before due to his recently obtained Upgrade Artifact. However, he finds himself Blessed With Suck due to the incredible physical strain it puts on his body, and he could accidentally Face Heel Turn at any moment and kill all of his companions.
 * Played with in Mirai Nikki, where some individuals who're not so mentally sound to begin with are given the ability to predict the future and told by God to kill each other highlander style. Whether the ability, situation or just generally being that nuts before drives them crazy is up for interpretation.
 * Pokémon Special uses this in the R/S arc. The Red and Blue Orbs can be wielded by mortals to control Groudon and Kyogre, but sufficient willpower is required to prevent loss of self. One Magma Elite tried and was driven mad; Archie and Maxie were so consumed by their lust for power that the Orbs wielded them.
 * The anime has Oakley in Pokémon Heroes, who loses it and tries to destroy the world once she gains control of a machine powered by Latios. Even her partner Annie is startled by the change.
 * Naruto:
 * Sasuke Uchiha seems to grow progressively more unreasonable, unhinged, and insane/evil the stronger he gets. Also the people responsible for making him what he is today, , all of whom display this trope to varying degrees, and all of whom passed a bit of that power and madness on to Sasuke.
 * Naruto also tends to head into this territory himself more than once. Not only does relying too heavily on the Kyubi chakra tend to result in him going into an unstoppable rage or transforming into fox-shaped chakra monsters, but if recent manga chapters are any indication,
 * Fairy Tail: This was the result of Elfman's failed Take Over spell against a monster called The Beast a few years before the story started. In order to save his older sister, he used his magic on a gigantic magical monster but wasn't quite strong enough to control it. He saved his older sister, and killed the younger. Out of fear of this happening again, he stopped using full body Take Over magic (eventually, he was able to control his power).
 * By the time Natsu fights Laxus during the Battle of Fairy Tail arc, Laxus has officially become so mad with power, he loses all reason, and tries to destroy everything and everyone.
 * Any Diclonius in Elfen Lied, except Nana.
 * In Saikano this more or less happens to She getsbetter. But then again...
 * In the original Fullmetal Alchemist anime, Ed gets a power overload from contact with a huge amount of unfinished Philosopher's stone and goes full-on uncontrollable with so much power it is described that if this goes on, he main attain enough power to be god-like(even freaking out the Homunculi) until a Cooldown Hug snaps him out of it.
 * In Puella Magi Madoka Magica almost all magical girls  Prime examples include
 * If piloting a Super Robot counts as "Great Power", then Neon Genesis Evangelion speaks for itself. The pilots, Shinji particularly, go mad from the experience of piloting the Evas.
 * If piloting a Super Robot counts as "Great Power", then Neon Genesis Evangelion speaks for itself. The pilots, Shinji particularly, go mad from the experience of piloting the Evas.

Comic Books

 * All attempts to replicate the Super Serum that gave Captain America his powers have ended up as Psycho Serum, either made people go crazy or been used on someone who was already crazy. In fact, in the Ultimate universe, this seems to be the origin for all of Ultimate Spider-Man's Rogues Gallery.
 * If you're a scientist introduced by name in the Spider-Man comics, you're usually one issue away from your experiments turning you into a deranged supervillain. Especially if your name conveniently sounds a lot like the type of experiment you're conducting...
 * One of the rare good endings for someone getting the Super-Soldier serum is Isaiah Bradley, grandfather of Patriot from the Young Avengers. Instead of going crazy with power, he simply lost a lot of his intelligence, sort of a super-Alzheimer's.
 * In almost every incarnation of Spider-Man, when he gains access to the power-enhancing abilities of the symbiote, and ends up becoming irrationally angry and cocky. Or, in the case of the movie, an emo.
 * Interestingly, this doesn't actually apply to the original comic book version of Spider-Man; he wore the symbiote suit for about a year without any ill effects, and it wasn't until the suit wanted their relationship to be a little more intimate than Spidey was ready for did he realize it wasn't such a great idea. The '90s cartoon was responsible for the "symbiote makes you a psychopath" aspect, which eventually came into play in the comic universe.
 * Spidey's archenemy, the Green Goblin, in his original portrayal, was this. He was a distant father whose business practices were not always scrupulous, but he had redeeming traits, such as genuinely loving his son, and saving Gwen Stacy's father's life. Then the formula that gave him his powers drove him insane, though periodic bouts of amnesia restored him to his former self. After he killed Gwen Stacy, however, he was rewritten as always being sociopathic, with the kinder personality that he possessed during his periods of amnesia being a false personality. The Goblin formula probably enhanced his insanity, however.
 * In the comic book series Hellboy, losing control of one's powers and/or humanity was a major theme of the series, especially for Liz Sherman and Hellboy himself.
 * That is to say: Liz burned her family to death by accident as a kid, and Hellboy doesn't and can't and won't use his flashier superpowers, since they mostly involve ending the world, but occasionally they get stolen, one way or another. His crown, his Name, his right hand, ALL THE BLOOD IN HIS BODY...
 * In Gold Digger, dragon hybrids between the tribes (Platinum, Gold, Copper, and Iron) are extremely rare and extremely powerful. Every single one has gone insane, however, with the sole exception being one of the comic's supporting cast, D'bra. And then, most dragons believe her temper is a sign that it's only a matter of time.
 * Apparently, Chris Claremont likes this one, or used to. In X-Men, The Phoenix being a cosmic entity was a Retcon to satisfy the then-editor-in-chief's requirement for bringing Jean back: she had to be innocent of her crimes as Phoenix. (The destroyer of five billion couldn't very well be welcomed back to the team with open arms. In fact, her original Heroic Sacrifice was mandated for that very reason.) The original story portrayed Jean's cosmic powers as the ultimate expression of her abilities, and the change from hero to Anti Hero to cosmic-scale threat as simply the result of having the sort of powers she now possessed. Storm also began a similar change upon maxing out her powers, but thankfully was able to return to her previous self (her power level returning to normal with it) within that issue and before she did anything particularly heinous.
 * The 'return' of Jean Grey in for the X-Factor retread of the original X-men was so badly done that it left permanent damage to the storylines of the Marvel Universe. The obvious moral cop-out of 'it wasn't really her' not only undid the basic point of one of the landmark storylines of the MU, but was done in a half-assed way, because they tried to claim that Jean deserved the credit for the self-sacrifice of the Phoenix entity, but not the blame for its crimes, even though both supposedly derive from the human element from Jean. Sorry, folks, you can't have that both ways.
 * To make it even worse, Claremont clearly hated the idea that the Phoenix entity was not Jean, he kept trying to sneakily re-retcon it back, and the story got into the hands of other writers and mutated further, it eventually became a total, unworkable, self-contradictory Continuity Snarl.
 * Oddly enough, though, Jean's time traveling daughter Rachel, who already had ample reason to have gone insane (but didn't) before acquiring the Phoenix power, managed to wield it for years without going crazy. And then lost the power (despite the Phoenix itself insisting that it had permanently merged with her).
 * More contradictory snarl. Though to be fair, in sealing up the M'Krann Crystal, Jean used the power on a scale Rachel never approached, so there's some excuse for the idea that Jean was more affected by it.
 * Long story short, Jean's power level, mental state, and the effect these have on each other all depends on where Jean ends and the Phoenix begins. Too bad no two mentions of the Phoenix in a row give the same answer on that score. However, the cosmic critter isn't malevolent. Mastermind screwing with her head was what turned Phoenix into Dark Phoenix, and to suggest it might happen again much later in Phoenix: Endsong, it took a botched resurrection to again put the Phoenix out of whack. Poor Jean will Never Live It Down, despite this.
 * Speaking of Mastermind and his plan to gain power through unleashing the Dark Phoenix, as Jean lost her mind and became the Dark Phoenix for Mastermind's evil means, she turned on him and ironically, gave Mastermind more power than he could ever comprehend, sending him into a coma (and insanity when he came to).
 * Claremont also established that classic X-Men adversary Magneto's magnetic powers damage his sanity over time. This explains rather a lot; wouldn't being able to control one of the four fundamental forces of the universe screw you up, too?
 * Magneto comes close to saying this trope by name in issue two of the nineties X Men series. When Moira Mctaggart explains how his powers played havoc with his mind he states: "What, with great power comes mental instability?"
 * Magneto's daughters, Polaris and the Scarlet Witch, suffer from similar sanity-damaging "cursed" powers. Insanity might be In the Blood where this family's concerned.
 * It's implied that the Scarlet Witch's crazy came from the Mind Screw the Avengers did so she'd  rather than from her powers themselves. Similarly, Polaris is only crazy when outside influence is involved... it just happens to her more often than it does to anyone else.
 * Considering Quicksilver, Magneto's son, also went a bit crazy when he gained a new power set after House of M, odds seem high.
 * Although, that wasn't the first time he'd gone a bit crazy...
 * This was Lampshaded in the Assault on Weapon Plus story arc, where the Weapon Plus files stated that super soldier experiments on criminals and psychopaths yielded less than reliable results, prompting them to find a different method of creating anti-mutant super soldiers.
 * Another X-related example has to do with Omega Red, the USSR's attempt to engineer its own Captain America-like super soldier. The brain trust in charge of the program chose a Serial Killer who'd been shot by his fellow soldiers for murdering children in his hometown. While initially a loyal operative, he eventually became too Ax Crazy even for the KGB and was put in suspended animation, at least until the Hand freed him. He now functions as a Psycho for Hire and one of the X-Men's deadliest foes.
 * The evil and non-evil versions of insanity pop up in a lot of the Marvel Universe's more powerful human characters, apparently as a way of Holding Back the Phlebotinum. Scarlet Witch, Phoenix, The Sentry, or anyone else like that being able to use their maximum power levels while fully themselves would remove all drama. Scarlet Witch is currently the most powerful and resultantly has it the worst. We haven't seen her mind in stable condition for quite some time now that her power's gone from "I point and my opponent slips on a banana peel" to "whatever I decide simply is. She'll never get to have that kind of power and the ability to think "Wouldn't it be nice if the Skrulls (okay, except Xavin, Lyja, and Cadre K, and the Super Skrull if he keeps playing nice) turned into rice pudding?" at the same time.
 * Apparently, getting hopped up on Chaos Emerald Energy in the Archie Comics Sonic the Hedgehog series makes you do crazy things. Examples:
 * Knuckles' ancestor Dimitri ends up becoming the insane Enerjak after absorbing some of the Master Emerald's power, one of the most powerful and evil villains in the series.
 * Knux's dad Locke, obsessed with the prophecies surrounding his son, genetically engineered himself and infused Knux' egg with energy from the Master Emerald in an attempt to fulfill those prophecies. They're more or less estranged, now, because of this.
 * Knux himself isn't safe from this, having recently appropriated Dimitri's mantle of Enerjak to avenge his race's decimation at Eggman's hand, only to quickly degenerate into "technology = evil" and attempt to wipe out all cybernetics from the planet, including those of the Dark Legion and his own girlfriend Julie-Su.
 * In the (non-canon) "25 Years Later" storyline, Knux ends up becoming "Chaos Knuckles" (a form he took up in the normal canon without much ill effect), and ends up trying to change the world, as well. The result was the almost complete destruction of his friendship with Sonic and the loss of his right eye.
 * In the future of an alternate universe, Knuckles not only tried to change the world, but he succeeded in conquering it after harnessing the power of the all the emeralds. He ripped the souls out of nearly all the main characters (Eggman, Sonic, Shadow, Tails, his own mate, etc.), sunk a continent, and then decided to try and amuse himself by conquering other dimensions. He uses the souls of his victims to create his Prelate Army. Oh, and he took on the name Enerjak in this timeline because "Enerjak the Hero" sounded cool.
 * Some versions of Sonic's Super form are like this, becoming a Super Powered Evil Side. This is mainly seen in the British Fleetway comics, where Sonic always becomes a psychopath when he changes to Super Sonic.
 * Such as the third season of Sonic X. Seeing a  gives a view of how upset Sonic gets when  . Combined with the 500-odd fake Chaos Emeralds nearby, Sonic turns Dark Super, shredding two test robots (based on speed and power respectively) in the blink of an eye, complete with the slightly unhinged giggle and a "Alright, Let's try 'em out!". It took a minute, and Eggman's logical prose to snap Sonic out of it, surprising somewhat as they've been at each other for years, and Sonic could quite easily rip Eggman to gibs.
 * In Archie canon, Super Scourge (Scourge being an evil version of Sonic who is already hyped on Master Emerald energy so this makes him even worse than a standard super form), upon seeing that his own world(Which he conquered) nor Sonic's own will accept him as King, says he's going to spindash both worlds in half just because he can, and will do this to one world after another until one gives him "the respect he deserves."
 * Sonic from the games actually becomes kind of crazy when he turns into Super/Hyper Sonic, at least in the old-school games on the Genesis. Suddenly goes from fast and cocky but vulnerable to fast and cocky and invulnerable, tearing through anything in his path. And way, way harder to control.
 * Matthew Cable from Swamp Thing. His Psychic Powers and his spiraling alcoholic insanity both stem from the same illicit electroshock treatments.
 * Warren Ellis' Global Frequency not only invokes this, but explains it in terms of the surgical alterations required to keep the superstrong bionic arm or whatever from physically tearing the body apart. "They gave him a mirror."
 * In newuniversal, which is also by Warren Ellis, John Tensen gains telepathic powers that let him "see" a person's misdeeds or ignoble intentions. The first time he used these abilities, he discovered that his own nurse was planning to poison him. Tensen, not surprisingly, became Ax Crazy and is now the "worst serial killer in New York City history," to quote a minor character.
 * In Powers, a naturally occurring variant occurs in "The Sellouts" storyline, in which a never-aging Captain Ersatz of Superman gradually loses his connection with humanity and goes insane, declaring himself to be a God. It's discussed that this may partly be a result of his ever-increasing level of superpowers, which go way beyond anything seen before (to the extent that the government has lied about exactly how powerful he is in order to prevent hysteria about him), and partly because, despite the fact that he doesn't look very old, he's at least over a hundred years old and has gone senile.
 * Deadpool was probably messed up before developing terminal cancer, but the Weapon X program (which initially failed to give him a Healing Factor) gives him a hard shove in that direction. Then Dr. Killebrew experiments on and tortures him to the point of having visions of (and falling in love with) Death. What finally demolishes his sanity is when Killebrew orders him killed, his healing factor finally kicks in, saving his life, making his disfigurement permanent, and causing Death to reject him. Depending on the writer, he's a mix of Ax Crazy, Deadpan Snarker, gleeful Genre Savvy and Medium Awareness.
 * DC Comics. The newest Kryptonite Man is a scientist who thinks Kryptonite (there is now a lot of it on Earth) can be used as a safe energy source. When he himself becomes that energy source, he decides to show the world how effective it can be by...a murderous rampage. That never ends well.
 * Later, in the same storyline, another scientist goes cuckoo bananas when he gains control over an oversized amoeba. Or so it seems. Superman subdues the guy, who says he didn't want to do it but Intergang, a powerful criminal organization, made him.
 * Retconned for Doctor Magnus, the leader of the Metal Men, also from DC Comics. He needs a careful application of medicine in order to stay stable and good. He's kidnapped along with genuine mad scientists and they cancel his meds, intending him to regress to his previous level of insane creativity, in which he created a horrific weapon of mass destruction, the Plutonium Man. Though he does recreate the Plutonium Man, he destabilizes very quickly, and with the help of several sentient robots he'd managed to cook up in his lab, invents a gun with living ammo and goes on a rampage (against evil men only), screaming about how he really needed his meds.
 * Handled interestingly with Marvel's Sentry. His powers are like some ridiculous combination of Superman and Franklin Richards, making him technically unstoppable and all-powerful. He's also a paranoid schizophrenic who managed to convince himself that there was an evil galactic power called The Void that would destroy the earth if he stayed a superhero... and then actually created it out of thin air, making a problem for The Avengers to handle while Emma Frost gave him some emergency psychotherapy. During this time, he also managed to Retcon himself out of his own universe, so that his Golden Age exploits all became some comic writer's fantasy. In something of a subversion, Sentry's not a villain: in current canon, he works to use his powers for a great deal of good. Unfortunately, his psychosis still isn't fully under control, and it's a disability that is sometimes just impossible to work around.
 * Recent developments suggest that the Sentry is an inversion of this trope. Robert Reynolds was already a mentally unstable drug addict before taking the serum that gave him his powers, so it's more like someone with great insanity given great power. Furthermore,
 * Mento wasn't the most stable/mentally healthy guy to begin with. Then he starts tinkering with a helmet that cranks his Psychic Powers Up to Eleven and takes up superheroing. But his wife (and her team) die, and it REALLY sent him downhill until he's doing stints as a supervillain and trying to kill his own adopted son! When that heroing team was led by a fellow Ret Conned into a Mad Scientist and Magnificent Bastard, it was damn near inevitable.
 * The Mask is this trope. Summary of every Mask story: Person finds the mask, puts it on, discovers they're a Nigh Invulnerable Voluntary Shapeshifting Reality Warper, starts using their powers in pursuit of some logical goal, loses sight of their goal and engages in wanton violence For the Evulz, is either tricked into removing the mask or removes it after a What Have I Become moment.
 * The Incredible Hulk. The gamma bomb gave Bruce Banner huge power and exacerbated his multiple personality syndrome. Plus, the madder he gets, the stronger he becomes.
 * Interestingly, for both The Mask and Marvel's gamma ray mutants, what happens to the subject's mind depends on what part of their personality they had dissociated themselves from. Most people who get the Mask unlock their evil side, but the fellow in The Movie didn't have an evil side, only a chaotic side, so he essentially became a Looney Tunes character. Marvel goes into more detail--Banner suppressed the rage that came from being abused as a child, She Hulk suppressed her sexuality, Doc Samson suppressed his desire to be a hero, and the Abomination suppressed his self-hatred.
 * Interesting case with Black Adam from DC. His powers don't drive him crazy, but he can share them, and anyone who would take them on immediately turns evil. Anyone, including.
 * When the Canadian government was looking for people to join Alpha Flight, they initially had trouble finding recruits. The people in charge of the program decided to try creating their own superbeings, and they got the bright idea to experiment on a Serial Killer who got a pardon in exchange for agreeing to participate. The result was a crazed monster with deadly psychic abilities calling itself Bedlam. Wolverine had initially signed on to join Alpha Flight, but this debacle was what caused him to leave the group in disgust.
 * In Zenith the alternate Earth Maximan, who had been superpowered since the 40s, ended up going completely insane and killing everyone on his version of Earth. That said, most of the '60s superheroes became somewhat less than rational by the time of the early '90s.
 * Arguably completely inverted in All Star Superman:
 * Similarly inverted (or not) in The Authority, where the Doctor gives up his powers to a previous Doctor, who was relieved of his duties for being a psychotic maniac. As soon as the full extent of his powers kicked in, he was overwhelmed by the empathy for every living thing in existence. Super-empathy being part of the Doctor's role as the world's shaman, makes you wonder why this guy was psychotic in the first place.
 * every Doctor gets a new power, added to the ones the Doctor who had the job had all the way back to the first one. after he went psycho the next guy got super empathy which he used A LOT of heroin to deal with.
 * Dr Manhattan is a subtler and relatively benign variation of the trope; it's implied that he was more at home dealing with elementary particles than other people even before the Freak Lab Accident turned him into an immortal Physical God who can see the future but not change any of it, even his own actions. However, instead of suffering a spectacular Heroic BSOD and subsequent Face Heel Turn, he's one of the least emotionally damaged people in the entire cast, whilst still being almost entirely disconnected from normal human thought patterns.
 * A rather mundane case of this appears in Incorruptible. Max Damage becomes stronger and more invulnerable the longer he stays awake. If he stays awake for say, a week, his powers reach Physical God levels. However, he is still vulnerable to the effects of sleep deprivation. The result is someone who is mentally exhausted and strong enough to topple buildings -- an unnerving combination. Dealing with the numbness his invulnerability brings with it for years has also taken its toll on Max's sanity.

Fanfiction
"Deirdre: You want me. And you hate it. I suppose it's only natural. I look a lot like don't I?
 * In the Oneiroi Series (for Order of the Stick), this fits Deirdre to a T. (Though to be fair, she had a few screws loose before she got the Great Power...)


 * , you've gone insane! Please lie down for a second. Take a deep breath. Calm down…

Deirdre: Of course I've gone insane! I'm infused with the magic from a being of pure chaos! But just because I'm insane doesn't mean I'm wrong…"


 * Shinji Ikari in Points of Familiarity.

Film
"It's amazing what you can do when you don't have to look at yourself in the mirror."
 * Bananas: After overthrowing the government of San Marcos, rebel leader Esposito declares himself the new president. Esposito also announces "the official language of San Marcos will be Swedish," "citizens will be required to change their underwear every half-hour" and "all children under 16 years old are now 16 years old." He spends the remainder of the film in an insane asylum.
 * X-Men 3: Jean Grey in her manifestation as Dark Phoenix. Although it is explained that she was already mentally unstable as a girl and her massive powers had to be reduced for her own good and that of everyone around her by putting mental blocks into her psyche. When these were removed, she started killing people with her mind. (This is actually closer to the original Phoenix story than the later comic and adaptation stories that portray Jean as having been Touched By Vorlons; see the Comic Books section above.)
 * In RoboCop 2, the evil corporation OCP attempts to build a successor to Robocop, but in all cases the new cyborg goes crazy and commits suicide. Finally, they stick the brain of a convicted, drug-addicted, psychopath into the cyborg. That doesn't work out too well in the end, either.
 * Honestly, you have to wonder what made them think that turning a convict into a heavily-armed weapons platform was a good idea.
 * Ironically, the scientists theorize that Robocop was a success due to the very qualities that made Murphy a good cop in life: his highly Catholic upbringing and stable family life imbued him with a strong moral compass, selfless devotion to duty and an aversion to suicide. Then they turn around and choose a murderous psychopath, because they thought that they could control him through his drug addiction. Umm... Nope.
 * Forbidden Planet exhibits this principle most chillingly through Morbius.
 * That was more of an Enemy Without, though. Morbius seemed sane right up to the end.
 * In the first Spider-Man movie, this is the origin of the Green Goblin. The process to make him a super soldier also seems to produce a homicidal second personality, a side effect foreshadowed by the formula's original flaw of driving a small percentage of the test animals violently insane. Ironically, Norman subjected himself to the serum in an effort to prove it would not have that effect on humans...
 * Doc Ock in the second film was made crazy by the robot arms. In fact, they slaughtered a room full of medical personnel while Otto was still unconscious. He overcame their programming just in time for a Heroic Sacrifice.
 * Same with Flint Marko in the third. He wasn't an especially good person before the accident that turned him into Sandman, but afterward he was just nuts. Eddie Brock, on the other hand, started out as a psycho; gaining the Venom symbiote just allowed him to express it in new ways.
 * Hulk: The most recent movie finds hardened veteran soldier, Emil Blonsky given a prototype super-soldier serum - to put "what I know now into the body of a man ten years younger". The combination of being defeated despite this and the taste of such power grow into the classic Comes Great Insanity.
 * Funnily enough, that serum is all but directly stated to be the one that gave Captain America his powers, but with Blonsky lacking the additional radiotherapy his insanity is a classic symptom of the Super Soldier serum gone wrong. Then he demands (against repeated warnings) a dose of an even more experimental serum from a much less reputable source and...let's just say the end results of that little cocktail ain't pretty.
 * Incidentally, in the comics this was power born of suppressed madness, which that power incidentally un-suppressed--he was a gamma ray mutant like the Hulk, and they all get personality shifts depending on what part of their personality they're suppressing. He had some serious issues, and they manifested brutally.
 * Universal Soldier. In the sequel, one of them even gets an artificially intelligent, Self-Evolving Thought Helix military supercomputer downloaded into them.
 * Hollow Man, starring Kevin Bacon. He goes nuts after gaining his abillity because he realizes he can get away with a lot of crimes while invisible. It goes from disgustingly creepy (opening a sleeping co-worker's top) to badness and murder real soon. There's some talk about the invisibility Psycho Serum causing insanity, but it's never made clear how much of an effect it's supposed to be having on him.

"Power doesn't make you good, David. It just makes you powerful."
 * As expected, the failure with Bacon's character doesn't stop the government. In the sequel, they use the serum on several more people, including a decorated soldier (Christian Slater), who also goes insane and starts killing people. Unfortunately, his soldier training makes him doubly difficult to kill. Unlike the scientist, who already had quite an ego, the soldier goes insane from an side effect of turning cells transparent. Since the skin no longer protects the brain from solar radiation, this causes unavoidable mutations and, as a result, insanity.
 * In Serenity, River Tam is a paranoid schizophrenic who suffers from hallucinations, delusions, post-traumatic stress, identity and memory disorders, and unfiltered emotional responses. All of this is due to government experimentation on her brain that gave her uncontrolled empathic Psychic Powers that tie in with implanted combat abilities that make her the single most devastating weapon in the setting.
 * Scanners.
 * In Scanners 2, this is Peter Drak's rebuttal to David Kellum when he tries to reason with him to use his powers for good.


 * Subverted in Amazon Women On the Moon, when Ed Begley, Jr. plays the son of the original invisible man. He creates a potion that he believes will turn him invisible but not insane. Unfortunately, he becomes insane but visible.
 * The Mask: Happens to Stanley Ipkiss whenever he wears the Mask (and when Milo puts it on as well). Dorian Tyrell, not so much. As explained above, the Mask unlocks the suppressed part of a person's psyche. Tyrell, a unrepentant criminal, already had all his nastiness full on the surface, so the Mask just made him invincible and monstrous.
 * The Craft: Nancy. It didn't help that she had a Dysfunctional Family.
 * Titan in Megamind mixes this with great immaturity.
 * Similar to Kefka Palazzo, it is hinted in Captain America the First Avenger that Johann Schmidt was the first person to receive the supersoldier serum, but for various reasons, namely a combination of the serum not being perfected yet as well as his dark inner nature, Johann Schmidt received a tremendous power boost at the cost of his sanity (and his human form).
 * from Chronicle. After a string of events lead him down the Despair Event Horizon, he snaps, and goes into full A God Am I, Omnicidal Maniac mode.

Literature
"Good necromancers are plagued by demanding spirits. They're taught how to erect the mental ramparts but, over time, the cracks begin to show, and the best necromancers almost invariably are driven mad by late middle age. To maintain their sanity for as long as possible they must regularly relieve the pressure by lowering the gate and communicating with the spirit world. ... Clairvoyants also live with constant encroachments on their mental barricades, images and visions of other lives. When they lower the gate, though, it doesn't quite close properly, and gapes a little more each time."
 * Night Angel trilogy by Brent Weeks: Dorian is one of the more powerful magicians in the book. He is immensly powerful in both the normal talent and the more addictive vir, and is said to be the best healer in living memory . But it is his prophetic gift that really gets to him. By the end,
 * Saidin, the magic used by males in The Wheel of Time, is tainted by The Dark One, causing inevitable insanity in its users. As time progresses, one of the main characters begins to show the effects of this, becoming schizophrenic, moody, and temperamental; halfway through the series, he seems like a completely different person, though he is under a lot of pressure... The Forsaken also have access to what they call the True Power, an extremely addictive, evil flavor of magic that also has serious psychological consequences; most would only consider using it under dire need.
 * Possibly exemplified best when some poor soul using Saidin breaks down AFTER ONE DAY, and starts screaming that there are spiders under his skin.
 * It's also worth mentioning that Saidin use can bring about other lovely effects, such as rotting flesh. It is entirely random as to which will affect you first, when, and to what degree.
 * Brandon Sanderson's Mistborn series:
 * Played straight and later justified in the third book with the Lord Ruler, a main villain.
 * Also true for the Lord Ruler's Dragons, the Steel Inquisitors. The Inquisitors use  This makes them supremely powerful, but is in no way good for their long-term mental health. All the Inquisitors we see in the series are somewhat... homicidal.
 * It doesn't help AT ALL that  provides an "in" for
 * Soon I Will Be Invincible, which even gives it a medical name: "Malign Hypercognition Disorder".
 * The One Ring in The Lord of the Rings.
 * The other Great Rings as well, especially the Nine, and, to a certain extent, the Seven.
 * Jacen Solo in the Star Wars "Legacy of the Force" novels seems to get crazier and crazier the more he falls to the Dark Side of the Force. He first justifies his actions as necessary sacrifices for the good of the galaxy, but by the end of "Fury," . They don't call it The Dark Side for no reason. The same applies to Anakin/Vader and a host of other Expanded Universe characters.
 * In David Brin's original novel The Postman, the brutal survivalists/Holnists are led by General Macklin and his aides, who were pre-war experiments on creating soldiers with superhuman strength and speed. The government chose the most ruthless, intelligent and efficient killers in its military, with foreseeable results when the US itself turned into an anarchistic warzone. Macklin is finally killed by George Powhatan, a later experiment of the same ilk, though with a nature loving Neo-Hippie as subject.
 * Midnight by Dean Koontz. Half straight, half inverted. A rather twisted scientific genius has designed microchip-like spheres that augment a person's mental and physical abilities, but suppress all their emotions except fear, which produces some rather odd behavior on its own. Then the townspeople begin to discover that an accidental side-effect gives them mind-over-matter shapeshifting powers, and they promptly escape into forms in which their lack of emotions doesn't bother them - either animalistic creatures without the intelligence to notice, or cyborgs without any emotion at all. Everyone dies.
 * In HG Wells's The Invisible Man, the titular character becomes a psychopath after discovering the ability to turn himself invisible.
 * In The Republic, Plato (writing Socrates' lines), tells a story about the Ring of Gyges, which gives the user the ability to become invisible. What does it get used for? The person who finds the ring uses it to seduce the Queen, kill the King, and take his place. Making this one Older Than Feudalism.
 * Evie Scelan: At the very least, most mages in the novels are highly paranoid. The title character aggressively cultivates a normal life to keep from going crazy herself.
 * Timothy Zahn's Cobra Trilogy has people being made into Super Soldiers and adjusting to new strength and speed and lasers in a matter of weeks. They're carefully screened beforehand; only the most emotionally stable ones actually become Cobras. Even so, a percent of them do not handle the transition well and develop something called a "Titan complex", the belief that one is so powerful that one is above normal laws and standards. Handing someone all that physical power at once, instead of having to acquire and use it in small increments, essentially sidesteps the usual adjustment mechanisms, according to the books. These people tend to decide that they know what's best and proceed to rebel until other Cobras either kill them or restrain them long enough to have the Super part downgraded. A major plot point is the main character, a Cobra himself, realizing that he has to help his colonies secede from the Dominion of Man and trying not to look like he's developed the complex.
 * Anthony Burgess' One Hand Clapping is about a man with hyper-photographic memory, who uses this ability to become rich, and show his wife the life she deserves. She later finds out not being able to forget things has driven him insane, when he reveals his plan all along; to show her the good life, before ending both their lives in a suicide pact.
 * In The Alchymist, one who goes the quick way to being "awakened" will not be able to comprehend the power, resulting in death.
 * In The Cycle of Fire, the process of mastering fire powers involves experiencing being burnt alive. The trainee must get past the pain to understand the flames, which usually requires sacrificing all capacity for empathy, making them a sociopath.
 * In the Dale Brown book Warrior Class, Fursenko suspects that Yegorov is suffering from this, the power conferred on him by the Fisikous/Metyor-179 turning him from a mild-mannered and intelligent person to a seemingly Ax Crazy Blood Knight.
 * Megan Lindholm's out-of-print novella "Wizard of the Pigeons" is based on a radical re-interpretation of this trope. Magic usually comes hand in hand with letting go of your previous life, memories, and basic perception of reality. Usually, the mage is so divorced from the outside world that he or she cannot hold down a job or personal relationship, and usually ends up living on the street. They also have to follow their own set of arbitrary rules and rituals, implicitly for thePlacebotinum Effect. Cassie has been doing this since the Trojan War, and is so uninhibited by her environment that she can bend reality to her whim.
 * Michael Swanwick's short story "The Promise of God" is based on the premise that using magic gradually erodes a magician's moral sense until they no longer have any concept of right and wrong; magicians are kept in check by being assigned guardians whom they are trained to obey without question.
 * My Work Is Not Yet Done by Thomas Ligotti: Zig Zagged by Frank Dominio, the Type V Anti-Hero narrator of the short novel, who manages to go violently insane before he makes his From Nobody to Nightmare transition, then proceed to lose it even more whilst simultaneously gaining more and more control of his extremely scary superpowers.
 * Ren Dhark: Inverted in one issue of this German SF series. At one point, the Terran world government decides to start a secret cyborg project with the help of a brilliant and highly ethical scientist. Thanks to very thorough advance evaluation and screening, the actual cyborgs turn out fine and become recurring supporting characters later on; instead, it's a candidate who gets turned down in the end (ironically precisely because he failed one of the psychological test scenarios) who goes a little Ax Crazy as a result, devises a plan to destroy the entire fledgling institute, and almost succeeds.
 * In the Keys to The Kingdom series, Arthur begins to slowly get driven insane the more Keys he gets, and almost uses the power of the Keys to kill Denizens several times, but luckily manages to stop himself before he ever does.
 * Twenty Thousand Leagues Under the Sea: The book subtly shows how Captain Nemo is slowly but surely losing his sanity by using the Nautilus as a Weapon of Mass Destruction: At the state of technology in 1869, a submarine could easily destroy any ship in the sea without possibility of being persecuted when submerges in the sea, so Nemo could easily cross the Moral Event Horizon once and again.
 * Heart of Darkness critiques Britain's "liberal imperialism" in the form of Kurtz who went insane because he has absolute power with no one to stop him.
 * In Kelley Armstrong's Women of the Otherworld series, this happens to necromancers and clairvoyants over time, and the more powerful they are, the faster their mental state degrades. Interestingly, necromancers can stave off the madness longer by using their powers rather than suppressing them.

Live Action Television

 * The 2000 The Invisible Man series starring Vincent Ventresca had the invisibility caused by a synthetic gland that excreted a light-bending substance, a secondary side effect of which (after a long enough period of time) was insanity, until the counteragent was administered - though this was only a plot focus once or twice. The primary side-effects were unpleasant enough that the invisible man usually got the counteragent before the secondary side-effects kicked in.
 * This was due to sabotage on the part of one of the creators of the gland. He intended to use the counteragent to control whoever possessed the gland.
 * Given that they explain Quicksilver Madness as being related to frontal lobe dysfunction, and the frontal lobes are involved in suppressing impulses, the main character presumably wants to be violent but is controlling himself. If they'd done the procedure on someone else, he'd probably have just had Attention Deficit Ooh Shiny.
 * This trope is applied in Stargate SG-1 to partly explain the evil megalomania of the show's main enemies, the Goa'uld: it's a side effect of revitalizing themselves with their all-healing sarcophagi too many times. When in "Absolute Power" Daniel Jackson asks to be given just a small portion of knowledge from the Goa'uld's ancestral memories, he is quickly shown that that would make him go wonky too. (See also You Are Not Ready.)
 * In an interesting twist, when O'Neill is exposed to "good" knowledge (twice), he also swiftly suffers mental breakdown; no evil megalomania, but his brain begins to fail from the strain of holding on to it all.
 * There's also the armband episode, in which O'Neill, Jackson and Carter get magic jewelry that makes them super-strong and -fast. It's rather subverted, though, in that the "craziest" they ever get is kind of impulsive and overconfident.
 * River Tam from Firefly. See Serenity reference above, as the extent of her abilities is only hinted at until the movie. She's still crazy in both, though.
 * Spoofed rather effectively on That Mitchell and Webb Look, with a sketch involving a man going insane with his power to levitate...biscuits.
 * In Supernatural, most of the people who are shown to have developed Psychic Powers like Sam go off the deep end. Doesn't help that they're designed with this in mind:
 * At the end of season six, after Jumping Off the Slippery Slope,
 * An episode of Farscape had the crew getting their hands on a powerful weapon that attached itself to the user, powered by an addictive drug with all the properties of TV steroids, which they needed to use to get Rygel back. Predictably, D'Argo, Aeryn, and Crichton all had to use it at some point. Thankfully, it had a built-in off switch - if the wearer lost consciousness, the weapon detached itself.
 * Heroes has Sylar, who went from a bookish watchmaker to a psychopathic serial killer after he began to acquire superpowers. Gaining those powers involves killing people and stealing their brains, so it's kind of a chicken-or-the-egg matter with him.
 * Season 3 episode 4 shows that
 * And how. As of Season 3 episode 24 (second to last episode of Volume 4) Sylar's latest power acquisition of combined with  has finally driven him completely bonkers, full blown Norman Bates-style crazy. It takes a lot to creep out Sylar but he finally managed to do it to himself.
 * The leader of The Company claims that mental illness are a side effect of the mind trying to cope with possessing superpowers, but it's likely he was simply lying to convince Niki to work for him.
 * Plus, HRG says after they capture Sylar that all the changes to his DNA have made Sylar more and more insane.
 * Mohinder became more aggressive and developed a compulsion to abduct people and store them in cocoons after injecting himself with his Super Serum.
 * Subverted pretty well in Season 3 with Scott, the Marine chosen to get the super soldier injection (a variant of the same serum referenced above with Mohinder). After he finishes twitching and panting, Scott glares at his benefactors, demonstrates his new super strength by throwing a chair hard enough to embed it into the wall... then smiles and nonchalantly remarks that he feels good. He spends his brief remaining screen time behaving quite sensibly until Knox sneaks up behind him and 360's his head.
 * Volume Five Big Bad Samuel Sullivan has been revealed to be this way.
 * In the third season of Roswell, Michael the sidekick ends up  and promptly goes crazy and.
 * One of the oldest TV examples of this trope is the Star Trek the Original Series episode "Where No Man Has Gone Before". As Gary Mitchell's god-like psionic powers increase, he becomes a callous megalomaniac, complete with Glowing Eyes of Doom. Dr. Elizabeth Dehner was able to restrain herself long enough to do a Heroic Sacrifice, perhaps because her training as a psychiatrist made her better able to psychoanalyze herself.
 * In the first series Star Trek the Next Generation episode "Hide and Q" the focus of the story is Riker's temptation with omnipotence, and how unlimited power takes away his self control and humanity, but fortunately Captain Picard helps him overcome the temptation to save lives and prevent natural disasters. Oh, he uses them to get rid of the space monkeys, so they didn't go to waste.
 * In Millennium, Frank and Laura's unique perceptions of reality lead to mental breakdowns.
 * In the 2007 remake of The Bionic Woman Sarah Corvus, Bionic Woman 1.0, goes crazy after getting her power.
 * There is a small story arc of Smallville where Batman's Green Arrow's scientific team developed a serum which heals the user of almost any injury, but seems to damage their minds in the process. Eventually Lionel Luthor uses it to save his son, which may or may not have helped his eventual turn into the full-time anti-Superman villain we all know and love.
 * A lot of the meteor freaks in Smallville end up going insane and evil. Granted some of the characters already have a screw (or several) loose before becoming meteor freaks (e.g. Tina Greer, Greg Arkin), but some only went nuts after getting powers. Sean Kelvin for example - before getting powers he was just a jerk, after he got powers he became a serial killer. Even the non-killing meteor freaks aren't always all right in the head (e.g. Cyrus Krupp). Also, when normal people get Kryptonian powers they tend to go nuts (e.g. Jeremiah Holdsclaw, Lana Lang, Eric Summers). Not all meteor freaks and normal-humans-with-Kryptonian-powers go nuts (Chloe Sullivan for the meteor freaks, Jonathan Kent for the humans-with-Kryptonian-powers), just most of them.
 * In The Greatest American Hero, Ralph (who lost the manual to his supersuit) meets a filthy rich old man who kept his manual and knew everything the suit could do. The guy used his suit to become rich and crush his enemies like bugs, and the aliens finally took the suit away. The old man thinks it's a good thing Ralph doesn't have the manual. At the end of the story, the old man gives the Lord Acton pagequote and says, "I wonder if he had a suit too."
 * A major plot arc in Babylon 5 that was mostly abandoned (but still hinted at) with Andrea Thompson's departure was the Psi Corps' attempt to solve the frequent insanity that accompanied telekinetic powers.
 * At some point in Doctor Who, the Doctor's companion, Donna Noble, The Doctor, unfortunately, is forced to give Donna a complete mind wipe of her entire knowledge of the Doctor/the TARDIS/the entire time she was on the show because  will slowly turn her so mad that it will kill her. This circumstance means that the Doctor can never see Donna again, as she will remember everything and go batshit insane with power and die.
 * Not really. It's not going insane with power that would kill her, it's that humans are physically unequipped to handle a Time Lord mind. Donna was still physically human but with a Time Lord consciousness, and it was going to literally burn her brain out in very short order, certainly before she had time to go mad with power.
 * A better example would be the Doctor himself. Despite having, essentially, the power of a god, he mostly averts this trope. Except that one time when he was pushed a bit too far, lost it spectacularly, and became, briefly, an example of this trope.
 * In the The Six Million Dollar Man, Steve Austin adapted to his bionic replacements very well, remaining well-integrated and with his reasonably decent moral sense intact. Not everyone else who was given/forced to take bionics did as well, Jaimee Summers was plagued with amnesia and mental troubles, another bionic man went the 'crazy with power' route as well. The implication was that power didn't necessarily go with madness...but it easily could.
 * In the Buffy the Vampire Slayer episode "Earshot," Buffy is contaminated by a telepathic demon. This has only happened to one other person, and it caused him to go insane and live as a hermit. Buffy is heading the same way when the Scoobies undo the effects.

Tabletop Games

 * It's never made quite clear whether the powers of the Awake from Don't Rest Your Head are an outcome of their madness and insomnia or the cause of them, but one thing is for sure: the madder you become, the greater is your power. The more you use your power, the madder you become. It's a slippery slope, and it ends with you turning into a Nightmare.
 * Justified in Exalted. After their defeat, the Primordials leveled the Great Curse against the Exalts, making them progressively insane. The madness of the Solars was the canonical reason for the Usurpation and the Sidereals decided to kill the Solars thanks to the Great Prophecy and their own Great Curse. The Solars, as the leaders of the Divine Rebellion against the Primordials, were cursed the most. The Dragon-blooded shock-troopers were cursed the least with the Lunars and Sidereals coming in between.
 * There's an even more direct example in Elementals. When an Elemental reaches Essence 10, it becomes a Greater Elemental Dragon, an entity of immense destructive power (possibly greater even than the most powerful Demons). All Greater Elemental Dragons to date have been utterly insane, to the point where they've needed to be imprisoned behind some of the most powerful safeguards in Creation (the Gardullis, Greater Dragon of Fire, is imprisoned within the Sun itself). It's speculated that this is because Elementals were simply never designed to be capable of coping with that level of power.
 * Also justified by Word of God for the Primordials themselves, most of whom are a) kind of crazy and b) have Crippling Overspecialisation written into their very beings. They have these traits because for most of their existences, they had been simply too powerful to face consequences to their actions, with even their weak points way outside the power level of anything not prohibited from fighting them. And then the Exalted came into play.
 * This phrase goes some way to defining Warhammer 40000. They've even got a Tagline for the game that goes: "Only the insane have the strength to prosper. Only those who prosper can judge what is truly sane." At least some of the Chaos forces admit it - "Sanity is for the weak."
 * Even Chaos is very, very thankful that The Outsider is still self-trapped in his box on the outskirts of the galaxy. We only know he's there because the Tyranids give it a hundred light-years of space to itself.
 * In the fluff backstory of Mage Knight, it was stated that mastering the opposing magics of Necromancy and Elementalism would drive a mage insane. The one guy who did went on to found the Atlantean Empire, which practiced slavery and subjugation.
 * Cyberpunk 2020 has humanity loss as a side-effect of cybernetic enhancement; as characters become more powerful, they start to feel disconnected from the meatbags around them. Eventually they go crazy, at which point C-SWAT has the job of taking them down.
 * Aberrant has a "taint" system, which is explained in that "No human being was meant to contain that much power." Taint works in a number of ways. You can purchase a new level in any ability at half price if you take a point of taint with it, and you also take a point of taint when your power reaches a certain level, etc. But no matter how good, or "taint-free" your character is, just remember that this is a prequel to Trinity, where it has already been set in stone that all the Novas went insane.
 * Not quite.
 * Call of Cthulhu introduced the Sanity (or SAN) stat. As your characters learn more about the Cthulhu Mythos, their Sanity slowly decreases until they go completely insane. Learning and casting magic also lowers your Sanity, as magic in the Cthulhu setting is a perversion of the natural laws that humans are accustomed to, but then again anything, even mundane stuff like seeing a shadow, can do that in CoC.
 * Cthulhu Tech, in the grand Lovecraftian traditions, is into this in a big way. Having a chip implanted in your brain so you can pilot the awesome Eldritch Abomination Humongous Mechas drives you mad slowly, being linked to an extradimesional symbiont that makes you essentially into a were-Lovecraftian Beast drives you nuts over time, learning both sorcery and enhancing your paraphysic abilities makes you crazy, and the Zoner parapsysics are normal people who a) got powers by going near a tear in reality that used to be Las Vegas and may be an intrusion into the body of Azathoth, and b) as you guessed, go very, very crazy.
 * Thankfully, this is also a setting where there are, in fact, therapists, and they're Genre Savvy enough to make their sessions a perk of military duty.
 * Rifts gives us the Mind Over Matter (M.O.M.) Works, a process that grants incredible strength, reflexes and Psychic Powers to its users via a set of tiny chips implanted in key spots in their brains. Trouble is, the chips slowly cause mental instability that gets worse and worse with time. The character type that has M.O.M. conversion is called, fittingly, the Crazy.
 * Vampire:The Requiem subverts the trope at a conceptual level with the new Ventrue, where a Ventrue vampire is more likely to gain derangements and go insane when called to make tests of humanity. And when would they need to make tests of humanity? When expanding their political power. And as the Ventrue are "Lords of The Damned", they would have a tendency to do this a lot....
 * And in the Revised version of Vampire: The Masquerade, the Malkavians, who have both MalkNet (a sort of hive mind of insanity) but also the super power to make OTHERS share a little insanity.
 * All oWoD had some kind of character that was completly out of its mind. Marauders, Black Spiral Dancers, Specters, every playable character in Hunter.
 * When the voices are real, are you still insane? But really, the Imbued of Hunter acquired more power the more they threw themselves into the Hunt, thus moving further away from humanity and its trappings (ethics, morals, emotions, etc), eventually turning into super-powered anti-supe fanatics who are human only in biological makeup.
 * And two of the creeds - the Hermits and Waywards - are broken right from the imbuing, since both get a direct pipeline to the Powers That Be.
 * True in Changeling: The Lost for really great Power --, they can lose all of their Sanity Meter in a matter of weeks. And it gets worse from here.
 * The Forgotten Realms setting has Sammaster, one of the mages "promoted" by Mystra to semidivine being status. This impaired his sanity, triggering a delusion (provoked by a ritual) that the goddess was infatuated with him, and the "friendly" advice of an evil priest made it even worse. He ended up stripped of power and convinced that dead dragons shall rule the world due to his bad translation of old prophecy. To fulfill this prophecy he created dracoliches and the infamous Cult of the Dragon.
 * Battle Tech features several types of neural interface technology that can boost battlefield performance beyond what's possible with just the usual manual/voice controls and neurohelmet, but are correspondingly more invasive and dangerous. Clan ProtoMech pilots, who depend on this kind of interface to control their smaller-than-regular-'Mech war machines in the first place, consequently tend to become increasingly unstable over time and usually die young.
 * This trope is one of the problems for magick-users in Unknown Armies. Adepts and avatars get their power by virtue of being so utterly obsessed with something (like drinking, or being the ultimate warrior) that it lets them alter reality. This means that most mages are a little nuts by necessity, and need to be pretty committed to their ideals if they want to become more powerful. It's no surprise that one of the big movers-and-shakers in the occult underground doesn't use magic at all.
 * This is also popular in Warhammer. All magic is made from the powers of Chaos, and chaos likes to reshape things into Eldritch Abominations. If a wizard uses too much juice the side effcts could range from his mind starts coming unhinged, to an explotion with a five mile radious. Being a worshiper of the Gods of Chaos also tends to do this as their warriors are trying to earn enough glory to become daemon princes, but most end up getting killed or turned into Chaos Spawn long after they go completly insane. Skaven can be described as this as their leaders tend to have a skewed view on things. Most Dark Elves could also count, especially with Malekeith.
 * Asyncs in Eclipse Phase are required to take one mental disorder for each level of the Psi trait they acquire because their powers come from a virus written by an alien entity that borders on Eldritch Abomination. And unlike other disorders taken during character creation they don't get extra character points for them.

Video Games
"Baron Praxis: The dark eco inside you will eventually kill you, Jak. Its destructive effects cannot be stopped. Once you are in its chaotic grip, it will not let you go until you slide into insanity."
 * This is the plot, or at least a sub-plot of every sci-fi themed video game ever made. Whether it leads to a Load Bearing Boss the player must face, or shows the player what he's become during the opening cutscene, is largely irrelevant.
 * Whenever anybody attempts to use the Orochi power in The King of Fighters series, it usually results in either death (Rugal Bernstein), insanity (Iori & Leona), or a God complex (Chris, Yashiro, and Shermie).
 * The Nameless One of Planescape: Torment gained immortality, but at the cost of his memory, which he periodically loses. Each reincarnation develops its own brand new personality, which is often insane. One of them was awesomely so. Another, one of the most dangerous, was mostly sane, but had the little problem of being a complete sociopath.
 * Kefka from Final Fantasy VI.
 * It's all but stated explicitly by a few NPCs in the game that the process that made him a Magitek knight before the game started turned him into a raving psychopath from the get go.
 * It was stated that he was the first test subject as well.
 * Final Fantasy VII has its own version; being injected with Jenova cells makes you powerful, but it also leaves you vulnerable to becoming Brainwashed and Crazy - which is what happened to Sephiroth (though it only started when he learned the truth). And Cloud.
 * Before Crisis plays the traditional version of it. After summoning Zirconaide, Fuhito's body is transformed as the as-of-yet incomplete summon expresses itself through him. He becomes incredibly powerful, but only retains a bit of whatever sanity he had left (he was kind of a Hojo Jr. already)
 * Interestingly enough, the only person that doesn't go crazy from Jenova cells is Zack. And we all know how that ended.
 * In addition, once Cloud is able to overcome the Jenova cells in his body, he never goes crazy again.
 * Although it is never specified if the Jenova cells caused Hojo to be brainwashed, his injecting himself with Jenova's cells (with an amount that obviously was a much larger amount than that of a SOLDIER), it certainly caused Hojo to become a lot more crazy.
 * To be fair, the Soldier process involved extensive training (I'm assuming there were others around, since it was the Soldier Program - known about by the people living under Midgar, at the very least), and, one would assume, psychological testing, well before any infusion of Mako or Jenova cells. Neither Sephiroth nor Cloud had opportunity for this, since the first was injected before he was friggin' born, and the other was just found as a convenient test subject (and we all know how great Hojo's morals are). Zack is the only on-screen Soldier who was created normally.
 * Other Soldiers are shown in Crisis Core, and they, too, are normal. (Genesis and  don't count, since they were in their own experiment)
 * Sin and Punishment places Saki (as well as his son, Isa, in the game's sequel) as the victim of this trope once he becomes a half-Ruffian, as Achi tells Saki that the only thing that can keep him from turning into a Complete Monster at this rate is by accepting his humanity by falling in love with Action Girl Airan.
 * In The Elder Scrolls: Morrowind,
 * The point is somewhat obscured by
 * One of the many side-effects of The Taint in Lusternia. Also a result of.
 * In Bio Shock, abuse of the mutagen ADAM, which gives the user incredible powers but often proves addictive, was one of the factors in the downfall of Rapture, the Utopia-gone-wrong in which the game takes place.
 * Andrew Ryan, on the other hand, didn't need the help to go from visionary leader of an Objectivist utopia to batshit insane dictator. He had no qualms selling Plasmids or ADAM to make a buck, but he didn't use them himself. His crazy was all down to the political power he had, and his desperation to hold on to it at any cost.
 * In the sequel,  is a good example of this.
 * Xenogears also features mecha pilots given performance enhancing drugs that cause them to go insane. This has caused the main female protagonist Elly a good deal of trauma as she's brutally murdered dozens of her fellow soldiers with her bare hands whilst under their influence.
 * Jeanne D Arc's
 * Queen Zeal of Chrono Trigger fame went mad with power when she came into contact with Lavos, plotting increasingly dangerous ways to drain its awesome power for personal use, even at the cost of her own kingdom.
 * Part of the problem with Fusion in Shadow Hearts is that doing so allows the demonic souls the Harmonixer fuses with to attack his sanity. In the first game, this is shown by having to pay a significant amount of the Sanity Meter to fuse. In the second one (and third, though that instead represents Shania losing herself in the power of the spirits), the fused character's Sanity Points run down at a faster rate instead. This is partially mitigated by how Fusion-capable characters start with much more Sanity Points than the rest of the cast (representing the incredible strength of will needed just to use the power).
 * And in the first Shadow Hearts we find that with great insanity comes great power,.
 * Giygas, the Big Bad from Earthbound, becomes so powerful in the end of the game that he is unbeatable save for one specific trick. On the other hand, his mind is completely shattered, so he attacks randomly while babbling nonsense.
 * In Earthbound's sequel, Mother 3,
 * In The Legend of Zelda Twilight Princess, several of the bosses Link faces off with have become corrupted by their possession of darkly powerful artifacts. A number of these, such as Darbus the Goron and Yeta the Yeti, were otherwise mild-mannered, friendly characters; the artifacts in question would grant their bearers extreme power and strength, but rob them of their sense and personality.
 * The Triforce itself isn't evil, but it does grant the wishes of those who touch it as a whole, or its parts, whether they are good or evil.
 * Phazon has this effect in the Metroid Prime trilogy, causing many normally gentle creatures to mutate and go insane. It becomes much more prominent in Prime 3 when it drives the other hunters insane.
 * This turns into a true horror when you see the "Corrupted" version of the Game Over screen in Metroid Prime 3; Samus is overcome by her Phazon corruption and.
 * System Shock:
 * SHODAN, who goes insane after her ethical constraints are removed, seeing herself as a goddess destined to inherit the Earth. Officially, SHODAN reexamines her priorities without ethical constraints and draws new conclusions. What were her priorities to begin with? One would assume, keeping the day to day operations of Citadel Station running smoothly. She was also overseeing the station's research projects intended to better humanity (and the corporation's profit margin) through the fields of bioengineering and cybernetics. Which explains a lot of what happened.
 * From the sequel: ", insect. Are you afraid? What is it you fear? The end of your trivial existence? I am SHODAN. When the history of my glory is written, your species shall only be a footnote to my magnificence."
 * Dark Chips in the Megaman Battle Network series (and its Animated Adaptation, Mega Man NT Warrior). Gameplay-wise, however, they're more of a Deadly Upgrade, increasing your power output but permanently shortening your lifespan.
 * Bionic Commando: Capcom seems to be setting up an implication in the new game in regards to this. However, it is subverted: people with bionic limbs are more or less sane (though in Rearmed, Spencer is one cocky son-of-a-bitch), but if they come to rely on the bionics and have them taken away...they kinda go Ax Crazy.
 * The backstory for the new BC game clears this up. The government gives soldiers bionic replacements for limbs lost in battle. Then, the government says that bionic replacements are dangerous and want to take them back. Which would be fine, except that the people who don't like the idea liken it to the government asking for parts of their bodies. Which is probably justified, especially in the case of people that have bionic eyes. Rather than give up their bionic replacements, these people join a terrorist group.
 * All in all... wouldn't you get a little annoyed if you were told that you had to forfeit your arm or leg?
 * In Breath of Fire 3, the Kaiser Dragon, if using the Infinity Gene without an attachment of some sort, is uncontrollable and attacks friend and foe alike. The Failure Gene weakens it to the point where it can be controlled. Subverted, however, if you use the Trance and Radiance genes along with Infinity; this creates the true Kaiser Dragon form, which is controllable and stronger than the regular Kaiser.
 * Somewhat subverted in Xenosaga - Albedo started going mad when he found out not that he was unable to die, but when he found out that other people did die. He began to fear his brothers' deaths and subsequently his being alone for eternity, becoming really morbidly obsessed with death
 * Jak and Daxter: If it doesn't kill them, Dark Eco can instill people with great power, for example Gol and Maia in the first game and Jak himself from the second game on. However, it also has a habit of driving people insane.
 * Somewhat subverted in Xenosaga - Albedo started going mad when he found out not that he was unable to die, but when he found out that other people did die. He began to fear his brothers' deaths and subsequently his being alone for eternity, becoming really morbidly obsessed with death
 * Jak and Daxter: If it doesn't kill them, Dark Eco can instill people with great power, for example Gol and Maia in the first game and Jak himself from the second game on. However, it also has a habit of driving people insane.

"Alex Mercer: The people I've killed...they're in me. I can hear them. See the things they've done. I can understand it all. I'm supposed to do these things...but it's right I can feel it..."
 * In Suikoden V, the Sun Rune is known to be one of the most powerful runes in existence. Even among the 27 True Runes, it's power is extreme, granting both the power to destroy a kingdom overnight, as well as being able to revive a country. However, it also causes mental instability, as the bearer believes themself to be equal to a God, completely infallible, and believing that anyone that disagrees with them should die a very painful death. The King of the ancient Armes Kingdom fell victim to this, destroying his entire kingdom in his insanity,.
 * Grand Maestro Mohs from Tales of the Abyss is a textbook example. He gets glyphs inscribed on him that flood him with Seventh Fonons to obtain the power of a Fon Master, but his body can't handle much of the Seventh Fonon. He immediately turns into a monster, then quickly goes insane. Subverted in that Dist, who applied the glyphs, knew exactly what would happen.
 * The Malkavian Clan from Vampire: The Masquerade Bloodlines. While they do gain all the benefit of vampiric powers when Embraced, they also inherit the clan's weakness (which oddly enough, happens to be their greatest power as well) - each Malkavian becomes incurably insane. And if that wasn't frightening enough, they can make you think whatever they want! Yup, their madness power lets them mess with your brain if they want.
 * In addition to that, Malkavians gain the unique power of insight. This isn't really obvious on your first playthrough, but in the second one you realize that Malks almost all the times know the answer before the question has even been asked. They even seem to know the plot before it unfolds, but they can't make sense out of it. Malkavians have these visions, but they cannot interprete them. They also seem to know the names of complete strangers, but it can be hard to recognize since they tell them in an extremely colourful language and use lots and lots of metaphors. Other vampires however can make use of the Malk visions, although it's implied to be extremely difficult to seperate the wisdom from the insane ramblings.
 * Also, while all Malkavians are a nutjob in some way, the player character is one of the really bad cases. The Malk elder of LA, Alistair Grout, seems to be pretty clear, even if he is suffering from a major paranoia.
 * Fire Emblem 8: To a slight degree, . In the supports between Duessel and Cormag,.
 * Also Karel in ""Fire Emblem 7". His madness drove him to constantly seek out and kill the strongest people he could find.
 * Utsuho Reiuji of Subterranean Animism was once just a simple, somewhat scatterbrained Hell Raven, until she gained the immense power of nuclear fusion. Then she immediately decided to torch down Gensokyo and turn it into hell on earth. Luckily, she gets better after a good beating from the PC.
 * In Spiderweb Software's Geneforge games, using the genetic-modification canisters created by the Shapers enables you to build your skills and powers very quickly; but also pushes you strongly into the "arrogant, violent, and insane" realm, which determines the sort of interactions you're able to have with NPCs, and which of the many game endings you'll achieve. In fact, the closest you can get to a Golden Ending (even the best endings are mixed) requires never using a single canister. Using the Geneforge itself guarantees you'll end up a sociopathic Super Villain; most likely a dead one. Some endings are so bad that they border on Anvilicious Author Tracts on the corrupting influence of power, and the evils of genetic engineering.
 * In Psychonauts those born with psychic potential can develop incredible powers and enter the minds of others. They also tend to range from seriously maladjusted to insane and few are actually all that eager to develop their abilities anyway.
 * In Prototype the main character is focused and driven, giving little outward sign of anything but rage and determination as he kills and eats his way through thousands upon thousands of soldiers, civilians, and zombies. Normally. But give him a moment to reflect on his situation and what he's doing and...well...


 * Not really an example, once we find out  "Insanity" here is really best classified as Loss of Identity, but you can't really call it that when
 * Arguably it's completely inverted since absorbing all of those people and experiencing their thoughts and memories, including their pain and fear, ends up giving him a conscience.
 * In Blaz Blue, we have Arakune, a scientist who sought knowledge from a place known as the Boundary, and got it. It had the unfortunate side effect destroying his sanity, turning him into, well,, and giving him the power to summon BEES!
 * Also, Blazblue characters that gained possession of Nox Nyxtoreses as children tend to be mentally unstable, at best, or outright insane, when sufficiently provoked. However, this is averted for characters that gained the said Nox Nyxtoreses after they turned adult - they tend to maintain their initial sanity/insanity.
 * Arguably  in Jade Empire. When you see the Emperor, he is quite clearly out of his mind,  .   seems pretty sane, and has it together enough to pull one spectacular Xanatos Gambit on your character. However, he obtains the   upon his brother's death and drains it even faster than his brother did. By the time you meet up with him for the final Boss Battle, he is very clearly out of his mind.
 * F.E.A.R's Alma is most certainly this. The more powerful her psychic abilities got, the crazier she got. And then they had to lock her away.
 * In World of Warcraft, magic is addictive, and magic addiction makes you insane. And it's hereditary, so the entire High Elf and Blood Elf races are addicts, whether or not they use magic.
 * In Portal 2
 * In Dragon Age II,.
 * Malefor, the Big Bad of The Legend of Spyro trilogy, was the first Purple Dragon and had all the power that Spyro can possess. The difference is he didn't know when to stop and let his power consume him, transforming him into a power hungry Complete Monster. His hunger for power was such that it forced his masters to banish him just to protect the dragons from him.
 * In Starcraft II, the Dominion-loyalist Ghost Nova proclaims that this is what happens to Spectres, an experimental form of "super-Ghost" who have their powers boosted by, among other things, exposure to Terrazine Gas. If the player chooses to ignore Nova's warnings and remain loyal to Tosh, the only free Spectre, and his plans for freeing his captured buddies, they learn that this isn't the case; Spectres are more powerful than Ghosts, but they were scrapped as a Dominion project because the upgrade process automatically blows their Restraining Bolt. Tosh, in fact, not only chooses only volunteers to become new Spectres, but deliberately screens them to ensure they are as sane and stable as is possible for a human with Psychic Powers in the Starcraft universe to be.
 * In the Modern Warfare series, this is what happened to Vladimir Makarov as the series progressed. Makarov started out as just a soldier in Zakhaev's army, and was promoted to Dragon status, but once Zakhaev died Makarov no longer had anyone holding his leash, and started a campaign of terror thanks to his newfound power. He eventually reached a point where he had virtual control of the entire Russian military, and was attempting to acquire the launch codes for Russia's nuclear arsenal as he wanted Russia to rule all of Europe, "even if it is just ashes."
 * Torque from The Suffering. Through gameplay, he fills a gauge called the Insanity Meter to transform into a creature that obliterates anything in his path.
 * In Shin Megami Tensei, it is stated as a very basic law of magic that it is perfectly possibly to turn yourself into a nigh-invincible powerhouse by fusing your human essence with that of a demon (or angel, for that matter). Sooner or later, though, you lose all of your humanity. This means you can get your power - but will never be able to exceed a certain point, with the added caveat you've now branded yourself a monster and permanently switched off your conscience. Death almost never fails to ensue. No wonder everyone seems so terribly interested in the Hito-Shura, the one case in which the fusion was carried out successfully - and the human ended up in control, meaning the demon power limits do not apply...
 * In the Rance World, if someone becomes a Demon King, they tend to go evil and berserk to better fulfill his duty to cause chaos and entertain the Whale God. This happens to a lesser extent if one becomes a demon, but it is more of a release of inhibitions than obligatory evil.
 * This also happens when one tries to wield Chaos for too long despite the sword being technically not evil. Rance is immune to his effects, however.

Webcomics
"Church: "Oh great, powerful and crazy. What a winning combo.""
 * Justified in Order of the Stick When V has spoken the Four Words he/she merges mentally with three of the most evil but powerful mages ever and therefore it's justified his/her mental state is a little vague thereafter.
 * The superintelligent gerbils of Narbonic, with the exception of the original, Artie. It's explained that, unlike Artie, the other gerbils weren't genetically modified to handle superintelligence, resulting in insanity. But when the sane superintelligent hamsters show up, they're megalomaniacs too. Also, the mad geniuses in the comic are only geniuses because they're mad; if their madness were cured, they would be Brought Down to Normal.
 * In fact, the genuises have to go past mad and out the other side...and then it's a crapshoot. Helen Narbonic reins in her crazy because of romantic feelings.
 * "This is sanity! SANITY!"
 * "Precisely."
 * Ian Samael of Errant Story starts to fall into this trope after obtaining godlike powers. To his credit, it did take
 * Girl Genius: The Sparks (or mad scientists) are often (although not always) insane. This is explained in the story as a side-effect of the Sparks' realization of their abilities (also known as the Breakthrough), which is usually traumatic to say the least. Some of the insanity seems to be inherent in the Spark itself; even the protagonist, the relatively sane and heroic Agatha, has shown utter singlemindedness and vengeful wrath while in the throes of a particularly Sparky moment.
 * This is implied to be happening to Ysengrin from Gunnerkrigg Court. He received weaponized wooden arms and Green Thumb powers from Coyote; after seeing him use them, Jones declared that he is "drawing closer to the brink of insanity."
 * And also, who's gained always-on ether-vision and the ability to fly while simultaneously losing a large chunk of sanity.
 * Turns out he was possessed though, so it's something else entirely (although the whole "not eating or sleeping" thing probably wasn't doing anything for him).
 * B-Movie Comic: In the invisible killer arc, the process that makes a person invisible can also make them quite frightfully deranged, but only if the person has a basic character flaw to serve as basis. The scientist then also use the treatment on Snuka so they can fight the invisible killer, on the assumption that anyone working closely with the professor must be a person of impeccable character. Not quite...
 * Red vs. Blue: The Meta has the abilities and A.I. of every Freelancer it has killed so far. That many A.I. in one body, however, have caused it to be more than slightly snarling mad. To the point where it doesn't seem able speak itself, only growl. (Church was naturally thrilled when he heard this.)
 * Red vs. Blue: The Meta has the abilities and A.I. of every Freelancer it has killed so far. That many A.I. in one body, however, have caused it to be more than slightly snarling mad. To the point where it doesn't seem able speak itself, only growl. (Church was naturally thrilled when he heard this.)

"Grif: "Simmons, I think you've gone mad with imaginary power."
 * Also in RVB, when Simmons takes power after sarge's "death" (he wasn't)

Simmons: "Oh no, Grif. I've gone mad with very real power.""


 * Cwen's Quest: This seems to be case with the Witch Queen. She is easily the most magically inclined character in the series and while normally smart she seems incapable for mentioning the word magic without bursting into bouts of insane Maniacal Laughter that would scare most versions of the joker. It is even more clear she is brilliant but insane in her Twitterings.
 * In Mark Shallow's current webcomic, Antihero for Hire, Wizard is an example of this, despite being extremely intelligent. Waterfall, an adversary using the same technology, snaps with the same kind of insanity at the sight of her sisters being threatened, which invoked Its Personal.
 * In El Goonish Shive, this is revealed to be the reason why Immortals "reset" every two hundred years. As time goes by, they become "more bored, more powerful, and less sane," which as Jerry notes is "kind of a bad combo." This could explain why  acts the way she does, since alleviating boredom through certifiably insane plots is her entire reason for doing things. She may have never "reset" in her life.
 * In Endstone, rocking the Banestone will drive the rocker crazy.
 * Dragos from The Beast Legion falls into this trope perfectly & it's clearly seen in the dialogue on the final page of Issue 2 . But he does have a great amount of power to back his claim.

Western Animation

 * Teen Titans: Raven must suppress her anger, otherwise she takes on a far more evil side that has no mercy and takes up a form that can border eldritch abomination
 * Superman the Animated Series: Luthortech has two examples of experimentation causing insanity.
 * Lex Luthor creates a super suit ostensibly to help the police fight crime. The officer testing it builds an unhealthy bond with it and becomes drunk with power, forcing the Man of Steel and John Henry Irons to take him down.
 * Irons later worked out the flaws in the suit that caused this behavior and created his iconic "Steel" armor. Interestingly, the first opponent he fights as Steel is Metallo, the below example.
 * Luthor poisons unwitting gangster John Corben, then offers to save his life with the Metallo project. Corben, advised only that there may be "some adjustments needed" to help him live a normal life after the process, accepts. But in his new robot body, the hedonistic Corben can't feel, smell, touch or taste anything, and becomes destructive in his rage at his human sensations being lost.
 * To be fair, Corben was already a criminal and card carrying psychopath.
 * In Ben 10 Ultimate Alien, this is revealed to be the reason behind Kevin's villainy in the first show. Absorbing energy causes insanity in people with his powers: before he'd even met Ben he was hooked on electricity and was planning to do things like crash trains full of people together to make a buck. After accidentally absorbing energy from Ben's Omnitrix he really goes nuts, and turns into a full on Psycho for Hire. After the Time Skip in Alien Force and Ultimate Alien, he is noticeably wary about doing it.
 * Aggregor claims that this is BS. However, since he is already an insane supervillain, he probably isn't the most reliable source.
 * Dark Danny of Danny Phantom arguably. Though the whole thing about watching helplessly as your family and friends get blown up and getting your super-powered ghost half removed did give a good start... but he only started a murderous rampage after getting his enemy's power. His past self is extremely horrified.
 * Vlad may also apply as he seemed to be largely content with his life before the accident.
 * Well, except that his one true love went and married their idot friend who Vlad thinks caused the accident anyhow.
 * In The Batman, when good cop Ethan Bennet becomes Clayface, he goes on a murderous vendetta against his former Captain. It's later asserted that the incident that turned into Clayface damaged his mind, and that, the more he keeps his form, the less unstable he will be. In fact, whenever he stays in his normal form, he's polite and rational, but the moment he uses his powers he tends to become violent and unhinged.
 * In Avatar: The Last Airbender Aang can enter the Avatar State, channeling the power of all his previous incarnations. You'd think channeling all those former Avatars would make him calm, wise and experienced, but no... Instead he gets all incandescent and frags everything in sight. However, true mastery of the Avatar State includes being able to control it,.
 * In the series finale, loses it.
 * In The Spectacular Spider Man, three Supervillains become as such when they get bonus mental instability with their powers. Electro and Doctor Octopus each suffer a Freak Lab Accident. Electro gets volatile electricity-based powers, then freaks out at his loss of humanity. Doctor Octopus' robotic arms are fused to his spine during a massive electromagnetic shock, which causes an extreme personality change. The Green Goblin claims that he suffered no blackouts and no change in personality from his Psycho Serum, but he may be in denial considering that he actually keeps acting crazy and speaking in rhymes while he's hovering above the prison in season 2 while no one can hear him.
 * In the case of Doc Ock it wasn't so much a case of the new powers messing with his brain, but rather stripping away his inhibitions.
 * More recently, John Jameson was infected by alien spores, which made him super massive, super strong, and essentially a Flying Brick without the flying, but, over time, messed with his head, making him filled with rage and aggression. After Venom threw him into a rage (making him think the one messing with him was Spiderman), Spidey was able to purge the spores from his system, making his body return to normal, but he was severely addicted to the power, and had to be admitted to an insane asylum. The effect was made more evident due to John having a cell right next to the now completely insane Electro, who babbles on about how he has no more human identity.
 * Eddie Brock would also qualify as an example. When he's stripped of the symbiote in a battle at Peter's high school, he is strapped to a stretcher and removed by two hospital orderlies, screaming at a crowd of spectators that "WE'RE VENOM!"
 * Dr. Viper was formally one of two biochemists who invented the Viper mutagen, which was intended to regenerate plants. Then he decided to try and steal it so he could sell it, directly leading to his transformation into the crazed, lizard-like Dr. Viper.
 * The otherwise peaceful Dr. Greenbox invented Zed, a robot that could repair any mechanical device. When said robot went on a rampage, he initially came along to help stop it...but was so delighted with how powerful his creation was that he tried to sabotage the mission and ended up merging himself with Zed.
 * An episode of Samurai Jack centers around Jack defeating three shadowy warriors with amazing powers who attack anyone who comes near. After the battle, it turns out that the warriors were actually three men who used a magic well to wish for the power to be the greatest warriors in the land. While the well granted their wish, it also made them blind and took their free wills.
 * Maria, from El Tigre is a mild mannered family women who is terrified of danger and hyperventilates when it is around her or her family. However, when she puts on her magical glove she transformers into the 'superheroine' Plata Peligrosa. If she only has it on for an hour she is fine, but a second longer and she becomes crazed and while do anything for a fight (even free crooks from jail). At one point she even starts attacking herself (because she has released villians and that is evil) and trying to kill HER OWN SON because he is trying to help her when she has labled herself evil and attacking herself.
 * Two examples from Beast Wars:
 * Rampage. A Maximal experiment to create an immortal spark, he is nigh-immortal but also completely insane and takes great pleasure from torturing others in the sickest ways possible. He's also a cannibal.
 * too. Once he, he goes completely bonkers and begins quoting the Transformer bible.
 * Optimus Primal had a couple of instances too. When he carried the spark of Optimus Prime, he not only got a new body out of the deal, but took on some of Prime's mannerisms. Prime was an incredibly good character, so Primal didn't get the nasty side effects Megatron got. In another episode, he gets injected with a serum that was supposed to turn him into a coward. However, it instead removed all fear, turning him into an unstoppable berserker. He didn't get stronger, just fully utilized his already considerable strength.
 * Ratchet on Transformers Prime goes nuts when hopped up on synthetic Energon.
 * Professor Lapton Professor Von Madman in the Buzz Lightyear of Star Command episode Eye of the Tempest after he tested his revolutionary crystal/human hybrid technology on himself. But he has a daughter...
 * In Static Shock, the Big Bang was occasionally thought to invoke this in earlier episodes. Notably, it's why Richie refused to trust Static when the metahuman Replay was framing him, believing that Static just took longer to go nuts then the others. However, since the Big Bang took place in the middle of a gang war, the guys who got the highest doses were generally not great people to begin with, and later episodes introduce other perfectly sane superpowered characters.
 * Inverted and then played straight in Re Boot. Hexadecimal started out very powerful and insane. When she gets reformatted into a sprite and as a result is depowered she becomes very sane and cheerful. But then she needs to go viral again to fight Daemon and the powerup makes her insane again.
 * Adventure Time has . An antique merchant from Just Before the End who put on a magic crown that gave him immense magical power and immortality... but also slowly drove him so insane he doesn't remember being any other way anymore.
 * Lemongrab. He's quite... "special," to put it nicely. Let's just say this "specialness" did NOT serve him, or anybody else, well when he inherited the throne to the Candy Kingdom. Being the result of a failed experiment, he has a lot of anger issues, and took out his anger on his subjects. To get him to leave the kingdom, the protagonists decide to play several pranks on him, which made his disposition even worse.
 * Freakazoid is the rare heroic example.
 * Spider-Carnage of Spider Man the Animated Series is an example of this happening to a version of Spider-Man himself.
 * The EVOs of Generator Rex can get hit with this, Body Horror, or both. The clearest example would probably be Breach, though she's at least coherent. No-Face from the Bug Jar also demonstrates a seriously degraded mental state, though not in the same way as Breach. And some EVOS are so far gone, it's easy to forget they were ever human in the first place.
 * Eerie Cuties arc "Doom Panties". Chloe always a shy nice girl, except when her friend shared a bottle and "her inhibitions just melted". When her Succubus powers got boosted, she began to "feel awesome" and put up quite a show, quickly rolling to the "scary" side. No malice at all, but Chloe won't let anything stand on the way of her fancy -- and since she got an excess of power to begin with, for almost anyone else it's a cue to take cover.
 * Nerissa of WITCH is a sad example of this. She was actually pretty well-adjusted until she gained control of the Heart of Candracar. The Oracle tried to cut her off at the pass, making her hand it over to her best friend, Cassidy. All it did was drive Nerissa farther into needing it, in which she killed her friend in cold blood. A good generation later, she comes back, pulling off a massive Xanatos Gambit to obtain more Hearts "for the greater good of the universe".
 * Nerissa of WITCH is a sad example of this. She was actually pretty well-adjusted until she gained control of the Heart of Candracar. The Oracle tried to cut her off at the pass, making her hand it over to her best friend, Cassidy. All it did was drive Nerissa farther into needing it, in which she killed her friend in cold blood. A good generation later, she comes back, pulling off a massive Xanatos Gambit to obtain more Hearts "for the greater good of the universe".

Web Original

 * Rick Point Blank: The plot revolves around a serum that grants a Healing Factor, makes you evil, and possibly makes you crave cookies and milk.
 * Pay Me Bug: Telepaths are in danger of going insane if they aren't trained to handle their power early enough.
 * The Questport Chronicles: The Master of Darkness, one of the most powerful sorcerers in the world, is also utterly insane. It's implied that part of this is due to returning from death.

Real Life

 * Adolf Hitler. Though potentially an inversion, in that he may have gained his power from his insanity. Memoirs of many German officials close to Hitler portray him as becoming increasingly, even violently, erratic; particularly toward the end of the war. Historians tend to attribute this to an increasingly self-destructive drug addiction. Amphetamine use was common in the German military at the time, and medical records show that Hitler himself was prescribed amphetamines in increasingly large doses, combined with barbituates later on to counter the side effects. Close to the end of the war, pilots were supplied with a formidable drug cocktail containing several analogs of amphetamine, cocaine, and morphine. The cocktail was quickly made available to submarine crews, and certain front-line combat units. It's believed that Hitler himself may have been using this particular combination drug by the end of the war, which contributed to his severe irrationality and eventual suicide.
 * The previous President for Turkmenistan made a large number of interesting decrees -
 * Did he have strong feelings about dwarfs, cats, garlic, and the color blue as well?
 * The Roman Emperor Caligula, who made his horse a consul (the Roman equivalent of Chancellor) and collected sea shells to prove he owned the sea.
 * More accurately, he claimed at a dinner party (full of hostile nobles) that he could choose to make his favourite racing horse a Consul if he wished. The sea shell thing was an aborted attempt to invade Britain, with him ordering the soldiers to gather shells and pebbles from the shore either so he could ride home through a Triumph because he conquered the ocean or to shame them for refusing to cross the Channel. There is a relatively small but persuasive claim that he wasn't really that mad, he just had a lot of unpopular ideas and an unusual sense of humour. The few accounts from the ancient world about Caligula were very much hostile to his rule and they don't entirely match up with other evidence from his reign (his coinage wasn't unusually debased, meaning that if he was mad he managed to be so cheaply for the state).
 * Interesting point. Didn't hear about the shells before, but it was prophesied that Caligula becoming emperor was 'as likely as him riding a horse across the Bay of Baiae.' After he became emperor, Caligula requisitioned all the ships at the port and had them tied up together to form a temporary bridge so he could ride his horse across the bay.
 * Modern scholars have come-up with some explanations for the stories about Caligula. He was made Princeps (ie emperor) when he was in his mid-twenties and effectively became ruler of most of the known world. His first few months in power apparently showed little sign of madness, with the emperor apparently taking his duties and office seriously. After these first months, though, Roman historians say he "fell ill" after which he "recovered" and that then the tyrannical and eccentric acts started. Modern historians have suggested that, taking into account that Caligula had already had a troubled upbringing, the pressures of enormous power and responsibility as well as the risks to him personally were too much for the young man and he suffered a severe nervous breakdown from which he never actually recovered. Although Caligula was arguably always cruel and sociopathic his breakdown removed any remaining self-restraint and Rome essentially had a dangerous lunatic as its emperor. Unfortunately, the absolutist system Caesar Augustus had created and the fierce loyalty of the emperor's bodyguards meant that little could be done about this until his assassination.
 * If it wasn't a nervous breakdown, other theories include him having a seizure, a stroke, or catching some kind of disease that affects the mind. About the cruelty and sexual delinquency, it is possible that the former emperor, his uncle, spent most of his time at his villa with little children who were his "servants". They would swim around in a hot tub with him and do things. When he was done with them, he would have them thrown off a cliff. It may go some way to explain Caligula's problems when you realize that a young Caligula stayed with his uncle. A history channel special outright stated that this is probably true and given the amount of research they do...
 * At least those rumors about the cause of Catherine the Great's death were just an urban legend.
 * One of the Oldest Ones In The Book, the Trope Namer for The Berserker. Old Norse warriors used to get hopped up on drugs resembling PCP to enhance their combat prowess. Such warriors knew they would not survive the battle though, and as such carried out their death rituals before ingesting the drugs. It's said that a bear-sarker needed to be hacked physically apart before he'd stop. When he did, though (and survived), he was extremely tired and dazed - again, much like someone coming off a drug trip.
 * One possible etymology of the word is "bear-sark", sark meaning "shirt", and it is suggested that berserks traditionally wore clothes made of bearskin in battle. Alternatively, it may be bare-sark, meaning they rushed at the enemy shirtless.
 * Some studies have shown that those with higher IQs are more prone to mental illness.
 * Many serial killers are highly intelligent people. For example Edmund Kemper has an IQ of 136 and Andrey Chikatilo being a very educated man and an avid reader (It's quite possible that he was only staging schizophrenic-like madness to avoid death sentence, as it looks quite overacted).
 * Artistic people are also famous for their high rates of mental illness. Well, True Art Is Incomprehensible.
 * The GIFT. It seems that anonymity and its inherent protection turns mundane people into massive Jerkasses.
 * And given a virtual environment to permit it, such as MMO's, much worse.
 * Any anonymous place on the Internet turns average men in epic trolls without any moral compass.
 * Cracked: 5 Most Shockingly Insane Modern Dictators and 7 Modern Dictators Way Crazier Than You Thought Possible.
 * Forensic psychology supports the theory that the motivation of a serial killer is often the thrill of having the power over other lives.