----
* By the end of ''Anime/SerialExperimentsLain'', most of the characters, major ''and'' minor, including to some extent, Lain herself.
** Hell, it's implied to happen all over the world.
---> '''Newscaster:''' Lets all love Lain! Lets all love Lain! Lets all love Lain ''[=LainLainLain!!!=]''
* Happens quite a few times in ''Anime/CodeGeass'', with results ranging from a HeroicBSOD to [[LaughingMad Insane Laugh]]... [[spoiler: to attempted hallucinogenics use. And attempted murder-suicide, on a couple occasions.]]
** Not to mention the final arcs of each season, though the second one is more ambiguous, depending on your opinion of Lelouch's logic (hint: [[spoiler: either bringing the world to it's knees and united in mutual suffering then assassinating ''yourself'' is a good plan, or Lelouch is mentally unbalanced. Or both.]]), the first is clearly [[spoiler:a plan to force someone to shoot you, then blaming them for it, with no obvious measures to limit the likelihood of dying.]] Not to mention Lelouch's attempt to [[spoiler: trap himself and his father in a giant chamber, devoid of food, dooming them both to starvation, if not for the insufficient explosives.]]
** One particularly notable incident from ''Anime/CodeGeass'' is when [[spoiler: Nina goes full on {{Yandere}}, to the point of showing up with a nuke to kill Zero, even though it would likely take everyone around with it, even her friends. She sounded beyond unhinged at the time, wild-eyed and shouting with grief and anger. Thankfully, it was defective...but then Nina switched to working on AppliedPhlebotinum {{fantastic nuke}}s. Oy.]]
* ''Anime/TengenToppaGurrenLagann'' has Simon going AxCrazy while fighting enemy mechas, locking himself on his room almost 24/7, and spending all his time carving statues [[spoiler:of Kamina]] out of stone. Luckily, he finally does a 180° flip.
* Makoto in ''Anime/RahXephon'' teeters on the edge until his grand scheme [[HoistByHisOwnPetard bites him in the ass]], at which point he takes the thrilling plunge into insanity.
* An entire episode of ''Manga/ElfenLied'' is dedicated to the AxCrazy protagonist Lucy's childhood, in which we get to see just how she got so unstable and murderous through this trope.
* In the 2003 ''Anime/FullmetalAlchemist'' anime, Scar's older brother is revealed to have suffered this. The combination of his lover's death, failing to revive her through human transmutation, losing his genitals in said transmutation, and the imposing threat of a war on his home eventually pushed him over the edge. Using his own body, he planned to create a Philosopher's Stone out of Ishval's people during the massacre. He wandered out onto the battlefield ''completely naked'' with AxCrazy eyes and tears streaming down his face as Scar watched in horror. It didn't end well.
* In ''Manga/{{Bleach}}'', Ichigo exhibited some Sanity Slippage [[spoiler:when his SuperPoweredEvilSide ''really'' flipped out and completely stomped Ulquiorra. Uryu tried to stop Ichigo from further slashing his body; he received a sword to the [[http://mangavolume.com/index.php?serie=bleach&chapter=bleach-353&page_nr=11 stomach]] for his trouble]].
* In ''Anime/RomeoXJuliet'', after witnessing [[spoiler:his father Titus's death]], [[spoiler:Mercutio]] quickly starts losing it. [[spoiler:And he ends up killing the murderer, Lord Montague, through quite the KarmicDeath.]]
* ''Manga/SoulEater'':
** Professor Stein goes completely insane as a result of Medusa's plans. [[spoiler:He got better]], but still the entire collection of scenes showing his descent into madness is creepy.
** Sort of applies to Soul Eater as well, [[spoiler:once he started using the black blood.]]
** The entire cast is constantly teetering on the edge of this trope. Madness functions as TheDarkSide in the ''Soul Eater'' universe, with characters falling into madness becoming evil and others resisting the temptation to madness. One of the major villains is someone who slipped so far into insanity that he became an EldritchAbomination.
** The manga-verse now holds that he's apparently insane because he's an EldritchAbomination personifying a kind of madness. Same point reveals that [[spoiler:Death the Kid]] is the next in line for slipping.
* In ''Anime/{{Gankutsuou}}'', we get this when [[spoiler:the Count of Monte Cristo watches Albert whom he had grown very fond of, leave his ship to witness the start of the Count's revenge on Albert's father.]] At first [[VillainousBreakdown he sobs desperately]] and then he breaks out into [[LaughingMad hysterical laughter]]. And from then on, he's out there, madly pursuing his revenge. [[spoiler:Andrea Cavalcanti]] also does this, going from creepy to outright deranged by the end of the series. And let's not forget [[spoiler:Danglar's DeathByMaterialism]], preceded by a good amount of madness...oh, and [[spoiler:Fernand Mondego, who snaps to the point of shooting his wife and son]]. Or Héloise de Villefort. Yeah, this show is pretty much filled with the trope.
* Gyagu Manga Biyori has the tale of the son and father who wanted to hire a tutor (and chose her more for the sake of [[DirtyOldMan her looks]] than the help she would give), but take many days to realize that they were tricked (Of course, like everything else, it is [[ParodiedTrope done in such a way that you have to laugh]]). At first they just look depressed when she doesn't show up, then their hands start bleeding because they clench their fists so hard and are beating the walls... their explanation for her absence is that they don't have a welcoming enough feeling in their home. Cut to them dressed as clowns as the father keeps stabbing a rock-hard cake while shouting "She won't come!" several times, [[LaughingMad mixed with laughter]]... It becomes an InvertedTrope when they then grab a hold of themselves and they work their way to becoming pure levitating Buddhists.
* ''Manga/{{Naruto}}'':
** Itachi displayed [[VillainousBreakdown this]] during his fight against [[spoiler:Sasuke]], while claiming that [[spoiler:his true plan was to get Sasuke to awaken his Mangekyo Sharingan so he could use his eyes to replace his own]], and suggests this is his true self. [[spoiler:It actually isn't, as Sasuke later discovers.]]
** Sasuke plays it straight, though. As if deciding to murder everyone in the Leaf Village weren't enough, he outright hits the floor in chapter 480 and the few after it. He's basically been reduced to a homicidal maniac who will kill anyone if they become the least bit inconvenient to him.
** Orochimaru went through this in his backstory, but managed to conceal it enough that he'd already been kidnapping people for depraved experiments for ages when Sarutobi finally worked it out. Nagato went through something more like a HeroicBSOD that resulted in a MadnessMakeover to Pain, but there was enough of a time spread that he definitely had time to devolve gradually. As {{Madness Makeover}}s go, wearing your murdered friend's corpse as a puppet avatar is pretty near the top.
** Gaara qualifies for this from his flashbacks. As a kid he was initially sweet and misunderstood. Then his father started sending people he loved to assassinate him. Fast forward to his early teens, and he's a homicidal maniac talking to sand as though it's his dead mother. Luckily he recovered.
*** Although as it turns out [[spoiler: he's pretty much ''[[TheCuckooLanderWasRight right]]'' about the sand. His sand automatically shielding him is basically his mother's spirit moving to protect him from harm.]]
** Kabuto lost quite a bit of sanity after [[spoiler: Orochimaru died]].
*** His backstory reveals that he suffered a significant dose of this when [[spoiler:he was nearly killed by his mother figure, who in turn didn't recognize him]]. Increasingly unsure of his own identity after years as a spy, only Orochimaru's intervention stopped him from cracking.
* [[spoiler:Ikuya Asano]] from ''Anime/TheTwelveKingdoms'' falls into this due to him getting closer and closer to the DespairEventHorizon as he's TrappedInAnotherWorld.
* ''Anime/NeonGenesisEvangelion'' has a cast that display their loss of sanity in different ways... some a little more disturbing than others.
** ''End of Evangelion'' decides to do away with the incremental slips and jumps right off the edge thanks to [[EldritchAbomination the ritual to awaken Lilith]] leaving [[GoMadFromTheRevelation Shinji a shrieking]] [[FreakOut broken mess]].
* [[{{Yandere}} Kaede]] from ''VisualNovel/{{Shuffle}}''. In the anime version, anyway.
* Sekai and especially Kotonoha in ''VisualNovel/SchoolDays''.
* ''VisualNovel/OokamiKakushi'': Issei in the few episodes he appears in until he [[spoiler:dies in episode 5]].
* Light Yagami from ''Manga/DeathNote''
* Dilandau Albatou from ''Anime/VisionOfEscaflowne'' is a subverted example. He was already kind of AxCrazy to begin with, but after Van [[spoiler: slashed Dilandau's face with a sword in a CurbStompBattle]], Dilandau's already fragile state of mind [[FromBadToWorse went downhill from there]].
* In ''Manga/SteppingOnRoses'' (''Hadashi de Bara wo Fume''), [[spoiler:Nozomu, who at first seems like a really NiceGuy gradually becomes more and more of a psychotic Yandere as the series goes on.]]
* In episode 7 of ''Anime/PuellaMagiMadokaMagica'', we can see [[spoiler:Sayaka]] breaking down ''fast'' as she fights a witch. Why? [[spoiler:Because a friend of hers had just told her that, in one day, she was going to confess to the boy Sayaka loved.]] That was just the last straw, though. [[AwfulTruth Other factors]] certainly [[BreakTheCutie helped]].
** By the end of ''[[Anime/PuellaMagiMadokaMagicaTheMovieRebellion Rebellion]]'', it's clear that [[spoiler:Homura may very well have left her mind in that Flower Field. And that's not even getting into what [[VillainousBreakdown Kyubey goes through.]]]]
* In ''Anime/GregoryHorrorShow'', the HellHotel can only be found by people who have already begun to slip a little (the first guest [[spoiler:may have been going mad with boredom from his monotonous life,]] and the second guest [[spoiler:starts to slip when her best friend marries her ex-boyfriend]]). Prolonged exposure to it breaks the guests more and more. [[spoiler:Both protagonists have completely lost their sanity by the end of the series.]]
* ''Anime/WeissKreuz'':
** Youji Kudou begins slowly losing his mind after [[KillTheOnesYouLove killing his would-be love interest]] before she could kill him first (although close scrutiny will reveal a few hints of it beforehand, such as a manga scene where he mistakes Omi for her after waking up from a nightmare). Before it's over, he's nearly killed several one-night stands and had several long conversations with the woman's ghost.
** Ken Hidaka doesn't fare much better: starting with the two-part OVA ''Verbrechen ~ Strafe'', he finds himself [[BloodKnight enjoying the act of killing]] more and more, goaded along by having to fake killing his teammates and having to ''actually'' [[KillTheOnesYouLove kill his girlfriend]] when she turns into a target. He manages to avoid falling so far as to start killing people on his own time, but in the RadioDrama ''Fight Fire With Fire,'' set after Weiss has been dissolved, he tries to convince Aya to become the new [[MissionControl Persia]] so that he'll have someone to tell him who he can kill.
* ''Manga/{{Gintama}}'': Yamazaki gradually loses his mind as a result of having survive on nothing but milk and anpan over the course of a month-long stakeout. First, he starts sparking anpan into the faces of random people, then starts seeing and hearing nothing but anpan, then finally snaps, with one of his log entries consisting of nothing but [[MadnessMantra "ANPANANPANANPANANPAN"]]. He never completely recovered from the incident, with him having random relapses in his insane behavior from time to time.
* Quite a few characters in ''Manga/PandoraHearts'' go through this at one point or another, like Leo after [[spoiler: Elliot's death]] or Oz when he goes into LoveMakesYouCrazy mode for Alice. (He gets slapped out of it by Gil).
* ''Manga/MiraiNikki'': Yukiteru. [[AxCrazy Yuno]] doesn't count because that would imply that she was sane to begin with.
* Mima and Rumi of ''Anime/PerfectBlue'' both experience this. Mima gets better but Rumi [[GoMadFromTheRevelation doesn't]].
* Koharu Mutsuki ''Manga/KoharuNoHibi'' acts more {{Yandere}} as the story progresses as a result of her love for Akira.
* In ''AudioPlay/SaintBeast'', Zeus becomes increasingly insane as the series progresses.
* ''Manga/TriGun'':
** A bit in-continuity, but mostly during the [=SEEDs=] flashback, after [[MuggleFosterParents Rem]] gets [[AllLovingHero Vash]] and [[OmnicidalManiac Knives]] out of the medbay where they learned the awful truth and promptly attempted to starve to death. Vash persists in wanting to die and hating humans, [[SelfMadeOrphan stabs Rem in the side]] in the course of a fight over a fruit knife he [[DrivenToSuicide hopes to use on himself]], and for a really awful moment, he '''[[SlasherSmile smiles]]'''. Then he breaks down crying, patches her up, and things start to be okay again.
** Notably, Knives didn't get this. Knives went promptly and utterly over to [[GoMadFromTheRevelation mad from the revelation]], and acted like he'd blocked it out and was perfectly okay right up until enacting Plan KillAllHumans.
** Legato also devolves steadily and horribly over the course of Maximum--yes, he was already bonkers, but after [[BigBad Knives]] [[MadLove breaks his spine]] he falls apart rapidly. Though he doesn't get less dangerous--after all PeoplePuppets are his specialty.
* Happens to Jeremy in ''Manga/ACruelGodReigns''. He could also have some possible MadnessMantra, at one point repeating "Hallelujah" over and over again while [[spoiler: Greg ties him up between his bed posts in a very crucifix-type manner and whips/rapes him.]] Jeremy also [[spoiler: laughs at the news of Greg's death (which he caused), tries to seduce his uncle, and plays mind games with Ian]] and generally seems unhinged the further the story goes.
* In ''Manga/AttackOnTitan'', several characters experience varying levels of it due to the very [[ShootTheShaggyDog nature]] of the [[CrapsackWorld world]]. Anyone that hasn't had a FreakOut, slowly gone mad, suffered a HeroicBSOD, or otherwise shown signs of coming apart at the seams probably died before they had a chance to crack. The trauma the survivors experience is a major theme, and teetering dangerously close to the edge is not only common, but completely understandable when the risk of being EatenAlive or watching your friends suffer the same fate is an everyday thing.
** [[spoiler: Bertholdt]] seems to become more and more hysterical after ''TheReveal''.
** [[spoiler: Reiner Braun]], after TheReveal. The fact that he's been teetering on the edge of complete insanity for a long time is particularly shocking, with his [[spoiler: VillainousBSOD]] continuing to get progressively worse.
** In a side story, an [[HumanoidAbomination Aberrant Titan]] is shown to be experiencing one. It goes from calm, to whimpering, and finally begins to cry while clawing at its own face until it nearly tears its own eyes out. Then it goes back to normal behavior, and eats the unfortunate soldier it had caught.
* The mother and father of sanity slippage: [[spoiler:Kars]] from ''Manga/JoJosBizarreAdventure'' ''Battle Tendency''. After attaining UltimateLifeForm status, he loses anything resembling sense. [[spoiler:And once he's thrown into space, he goes so insane ''his brain shuts down''.]]
* Liang Qi, not the biggest bastion of sanity to begin with in the ''{{Anime/Canaan}}'' series, rapidly starts slipping after Alphard, who she has an obsessive devotion for, abandons her, resulting in a VillainousBreakdown that ultimately leads to her [[spoiler:having to be given a MercyKill after she gives herself a dose of the Ua virus in a mad bid for Alphard's attention, only to learn very painfully that she doesn't have the genes for synaesthesia]].
* It is made fairly obvious that ''{{K}}'''s [[StalkerWithACrush Fushimi]] [[{{Yandere}} Saruhiko]] was not born AxCrazy. But because LoveMakesYouCrazy and Yata Misaki [[ObliviousToLove is pretty dense]] he starts resenting HOMRA and defects to SCEPTER 4 because [[AttentionWhore if Misaki hates him he will finally pay him some attention]]. Memory of Red and Days of Blue show clearly how much it pains him but even Misaki outright trying to figure this out did nothing to snap him out of it. It's rather tragic, especially when you see his PsychoticSmirk which, at the same time, is the happiest you'll ever see him.
* Happens to [[Manga/TokyoMewMew Kish/Quiche]]. What starts off as a simple VillainousCrush soon turns into MadLove. Towards the end of the series, he turns into an AxCrazy StalkerWithACrush who is NotGoodWithRejection. [[spoiler:This changes in the ending where LoveRedeems.]]
----