Trauma and tragedy tend to follow characters like plagues, and they often break them down, turning them into insane, jaded shadows of their former selves. This can often happen in various ways, but the best way to tell if a character just can't take it anymore is if they just break down and start laughing for no reason at all, or for all the wrong reasons. Usually, when this happens, they will continue to sit there, laughing uncontrollably, as if in a trance, until someone breaks them out of it, sometimes by a slap in the face.
Expect the laughing character to either gain control of themselves and apologize for losing it (while still emotionally fragile, of course), or, alternatively, simply stop caring about life. This may lead to them becoming distant, or become more harsh than before.
More often extreme cases occur, causing a character to turn to complete madness, either going into an insane asylum or possibly twisting them further.
On the flipside, villains are also prone to this. It is often shown as being fundamentally different than an evil laugh, usually shown as them either laughing a lot longer than normal, having the laugh sound more deranged than cold and boastful, or a combination of the two. This is normally shown if the writer wants to characterize the villain in a much more psychotic light and have a more frightening nature than normal. Expect it to also be used for a Villainous Breakdown in some cases.
Like Insane Equals Violent, this phenomenon is rare in real-life instances of severe mental illness. In fact, a common characteristic of schizophrenia is the absence of laughter, or indeed of other indicators of emotion ("flatness of affect"). Of course, the Truth in Television here might come from Bipolar Disorder, where mania causes inappropriate laughter on a euphoric scale — or Schizoaffective Disorder, which is the two in a blender. Then there's the simple fact that inappropriate laughter can accompany intense grief or anger, without actual mental illness needing to be involved - a related phenomenon is "hysterical laughter", where an intense bout of Inelegant Blubbering starts to resemble a laughing fit.
Not necessarily related to Evil Laugh, but definitely a type of Freak Out. Is also a sure-fire sign of Sanity Slippage. Also see Put the "Laughter" in "Slaughter" for maniacs who engage in this regularly, and Giggling Villain for a constant if contained laugh. Sometimes overlaps into Die Laughing, especially if it is the result of a Villainous Breakdown.
Not to be confused with Final Fantasy VI's Dancing Mad, although that game did act as the Trope Namer in regards to its main villain.
open/close all folders
Anime and Manga
In Steins;Gate basically every time Hououin Kyoma enters the scene, though it's actually just an act.
Franken Fran: Mr. Umimiya appears on the verge of a laughing nervous breakdown upon discovering his long lost daughter Ruri's (whom a maniacal cult worshipped as their prophet) body had become a part of the facility they're standing in due to the cult requesting Fran that she create an enormous artificial body when she fell ill.
In fact, the first thing you see in the second arc, even before the opening, is a scene of Rika stabbing herself in the neck while Shion laughs maniacally. It then takes about 10 episodes before you're finally told the context, and that makes it even creepier.
For your viewing pleasure, someYouTube Poop of Shion laughing...for ten minutes.
In the intro of Paranoia Agent, everyone is laughing. In the most unlikely situations, such as a guy in freefall, a drowning woman... what better way to tell you're about to get mindscrewed?
Also, the deleted scene where Light stays in the graveyard after L's funeral, starts laughing madly, proceeds to crawl on top of L's grave and shouts "What do you think of that, L? This is my perfect victory! That's right—I win!" with a crazed look on his face... and looks suspiciously like he's humping L's grave.
Full Metal Panic!. Kaname has a crazy laugh that she gives whenever she's lying about something — such as the possibility of being attracted to that nutcase Sōsuke. Or denying that his latest bone-headed antic bothers her in the least. Be afraid. Be very afraid.
In Barefoot Gen, Gen's mother Kimie falls into this. It's quite appropriate after watching her entire family burn to death amongst their pleas for help.
The most striking would have to be after his fight with Medusa, with Stein breaking into a lovely example as stands with his scythe as the witch's blood rains down on him. Madness, apparently, feels good.
Anyone under the influence of the Black Blood would do this. Crona and Maka are examples.
Not to mention Hidan of the Akatsuki. This guy wasn't sane to begin with, but once he gets into his rituals...
Gaara has a great one during his fight with Naruto.
In chapter 356, Kabuto has lost quite a bit of sanity following Orochimaru's death and reveals he has absorbed Orochimaru's remains. At one point he bursts into hysterical laughter.
In chapter 577 Kabuto does this after talking with the resurrected Itachi.
Andrea of Gankutsuou is not exactly sane. One of the ways he shows this is by giggling/laughing creepily at random times.
In one scene, the Count watches Albert leave his ship, quite peeved with him. Although we're led to presume that the guy is deep in grief over the event, we quickly see him break out into hysterical laughter. And from then on, he's out there, madly pursuing his revenge.
AloisTrancy of Black Butler II out of nowhere breaks into hysterical laughter when he's alone in his room in episode 1 to help show how insane he is.
On the other side of the spectrum, Ciel gives us an absolutely geelful one after the circus arc, when he travels to the workhouse only to find out that it's in ruins. It's frightening in context, considering that the revelation would mean that the circus children all died trying to protect nothing.
Broly from Dragon Ball Z definitely applies, especially in the flashbacks where it is clear that his laughter was uncontrollable after destroying at least one planet as a child.
Frieza also gives one off while destroying Planet Vegeta. Well, he did seem a bit too exhilerated at blocking Bardock's attack as well as destroying Planet Vegeta.
Akuha does so at the end of chapter 53 after breaking down and seeing Moka with Tsukune.
Berserk, with all of the madness that happens in this universe, expect it to happen a lot.
Jill laughs during the climax of the fight between Guts and Rosine, when the slimy, deformed corpse of a child that was undergoing Rosine's apostle spawn transform spilled from its cocoon. Jill remarked that the experience pretty much ruined her childhood.
In Princess Knight, when Friebe finds out that the brave knight she planned on marrying was really a princess in disguise, she bursts out laughing and shouts "That's too perfect!" She pulls herself together and agrees to help the princess escape her pursuers.
Jeremy when he finds out that Greg's car crashed thanks to Vehicular Sabotage and when he is moved dorms because he kissed his roommate William. He laughs because he finds it ironic that he gets in trouble for kissing his roommate, yet he is sexually abused every weekend which leads William to Get Ahold of Yourself Man in A Cruel God Reigns.
He stood in the middle of it all in a puddle of blood as more poured down his front and it was almost ironic that a few heartbeats later Harry was hit by another stray curse. Clark had joined the fray with his mother and luckily his jinx was almost harmless. It only banished the top part of his clothes away and that was when Harry started shaking. In the end it wasn't the teachers that stopped the chaos building inside the ballroom…it was the sound of sharp cold laughter.
It pulled everyone's attention as they turned their eyes to Harry who stood bleeding with a star burst wound on his chest blood flowing from him steadily as he laughed. Harry laughed harshly with no humor as he raised a shaking hand to his face inspecting the blood painted on it before he fisted his hair with both hands and cackled brokenly. Blood was smeared across his face; he was covered in spatters of blood giving him a ghastly image. The cool rush of the air reminded him that now most of his worst scars were on display and made him cackle harder.
Twilight Sparkle in Pages Of Harmony does this several times, one of the more notable ones from Chapter 11 when she's bleeding from wounds caused by an Ax-Crazy Fluttershy after Kindness has been taken.
"Ha, I'm no masochist, my friend!" Twilight was shaking her head in response to the other pony's inquiry, gasping for breath from her half-shrieks. "Heheh, haven't you heard that, hahaha, laughter a way to trick your body into, haha, not feeling pain?!" Her smile widened as she managed to dodge Fluttershy's frenzied attacks, angling herself to more easily control the blood flow from her wound. "Heheheh, that's why I laugh, Fluttershy! It enhances me! I sill feel pain, but, heheheh, it's not enough to kill me!" Her eyes were bright despite the obvious pain in her body, practically drunk with the imagined extent of her plan and the laughter which accompanied it. "Imagining helps too, just as I'm doing now, ha, thinking of just how existence will be when I've helped purify it under my guidance as a good friend and teacher! Hahahaha HA!"
The Lion King has The Hyena, Ed, who communicates entirely with crazed laughter. Banzai and Shenzi also qualify, but to a lot lesser extent. Cancelled storyboards indicated that Scar would have undergone a heavy dose of Laughing Mad shortly after throwing Simba off Pride Rock before being consumed in the flames that destroy Pride Rock.
It was also originally intended that Gaston from Beauty and the Beast would have undergone similar reactions to The Joker from The Dark Knight when falling to his doom upon stabbing the Beast (ie, proceed to laugh maniacally while falling).
Vanessa, the disguise for Ursula in The Little Mermaid, started laughing frequently and somewhat dementedly while gloating about her inevitable victory, indicating that the transformation process costed her quite a bit of her sanity.
In The Hunchback of Notre Dame, Frollo laughs evilly as he goes to stab Esmeralda with his sword. Given that his next line suggests he thinks he's doing God's will ("And he will strike down the wicked, and cast them into a fiery pit!"), it's pretty likely he'd also gone mad with power.
Subverted when Jafar starts laughing for seemingly no reason while he's being searched for by the guards, causing Iago to think he's gone insane, but then he stops and explains that the genie lamp he thought was Lost Forever was in the hands of "Prince Ali."
Played straight by Jafar during the Prince Ali Reprise.
Buzz Lightyear in Toy Story does this after realizing he's just a toy. ("You see this hat? I am Mrs. Nesbitt!") He stops after Woody slaps him with his own detached arm.
Films — Live-Action
Richard Attenborough's character in The Flight Of The Phoenix 1965 when he discovers that the man building the plane to take them out of the desert, and save them from slow and painful death, only has experience designing model airplanes.
Norman Bates occasionally laughs at inappropriate points during his dinner with Marion in Psycho. He also lurches from laughter to complete seriousness a couple of times, which is equally scary.
Beyond Re Animator: After Philip's girlfriend is murdered, Dr. Herbert West brings her back to life by infusing her with the lifeforce of the corrupt warden who killed her along with his previously developed reagent so she can retain her memories, skills, and motor functions as a zombie. Unfortunately she comes back as a kinky crazed and dangerous zombie and Philip is forced to incapacitate by cutting off her head. When the guards find Philip weeping over her headless corpse, they drag him away as he tries to convince them that she is still alive by urging her and her headless body to speak to them. When she doesn't respond, he goes into a fit of insane laughter and then when he and the guards are out of sight, her head starts laughing and thus the movie ends.
In many Hamlet adaptations Ophelia's madness is like that: she switches between sadness (tears) and moments of happiness (insane laughter).
Chief Inspector Dreyfus in The Pink Panther Strikes Again has a small bit of this after being "saved" by Clouseau on the day of his sanity hearing, triggering his escape from the asylum and sending him on a course to try to Take Over the World.
Baron Vladimir Harkonnen in the 1984 film adaptation of Dune definitely qualifies, given how the film basically made him even more deranged in it than in the book or the TV miniseries.
The Joker from The Dark Knight embodies this trope. Heck, he was even laughing when about to face certain doom before Batman saved him from hitting the ground.
In the 1989 Batman film, the Joker laughs a lot during the film, with him going way off the deep end near the climax when he is taunting Batman and Vicki while they are hanging for dear life. Joker even lampshades it in the same climax, where he goes into a fit of laughter, turns to a gargoyle behind him and yells "What're you laughing at?!" and then resumes laughing.
Austin Powers in Goldmember had Dr. Evil dunking the Japanese Corrupt Corporate Executive Mr. Roboto into his "sharks with lasers on their head", which were gifts from his son Scott Evil. Although Dr. Evil and his followers did a simple Evil Laugh, Scott Evil's laughter, as well as Dr. Evil's horrified reaction to Scott Evil's amount of laughter, was more similar to Laughing Mad.
After a long and miserable afternoon watching his dream home literally go to pieces on him, Walter and his fiancée Anna in The Money Pit try to prepare a relaxing bath, only to have the tub sink through the floor and shatter into smithereens in the foyer below. Walter's reaction is both a sterling example of this trope, and one of the funniest parts in the movie.
Data in Star Trek: Generations briefly goes laughing mad while attempting to investigate with Geordi the space station that Dr. Soren was working on, due to a combination of both the dampening field in place as well as Data's emotion chip going beyond his control.
In 8 Heads In A Duffel Bag, one of the main character's best friends goes exactly this kind of crazy after having been tortured by a Mafia hitman, repeatedly told he's going to be killed, and forced to cut off the heads of cryogenically frozen people as replacements for the missing ones, among various other extremely stressful events. The final straw was when the aforementioned hit man started talking about using his head as one of the replacements. He spends the rest of the movie getting worse
In Donnie Darko, Donnie laughs hysterically when he finally comes to terms with the fact that he's going to die and is waiting to be crushed by the airplane turbine.
In the film adaptation of The Wizard of Oz, the Wicked Witch of the West frequently bursts into hysterical, exhilarated laughter whenever pain and suffering caused by her is happening.
Done by the fowl villain Nigel (pun intended) in Rio, a bitter and sadistic cockatoo whose replacement in a popular animal show by a green parakeet caused him to develop a deep hatred against all exotic birds. He lets out a maniacal laugh after his Villain Song "Pretty Bird."
In Eye for an Eye, Karen McCann starts laughing hysterically during her daughter Julie's funeral.
In the 1951 Scrooge 1951, when Scrooge wakes up on Christmas morning and can't stop laughing out of joy, his housekeeper thinks, justifiably, that he's gone quite mad.
Priscilla Queen Of The Desert: Adam/Felicia is running for his life, in heels and a dress, from a pack of enraged Australian rednecks... and he's laughing his ass off'' until they catch him.
In The Truman Show, Truman bursts into laughter several times when he tries to call out his "wife" on the fact that the world he's in is fake.
William Faulkner's Darl from As I Lay Dying. Near the end, he goes insane and when he's not reciting a Madness Mantra of "yes, yes, yes, yes...", he's laughing his head off.
Bellatrix Lestrange from Harry Potter. All the freaking time.
Sirius Black - after his best friend James Potter and his wife Lily Potter died, started laughing as he was arrested although he was in fact innocent. The laughter was probably a combination of all the emotions piled up on him, likebetrayal, grief, and hatred.
During the big fight at the end of book five, Ron gets hit by an "Intoxication Ensues" spell and becomes uncontrollably giggly despite still being in mortal danger.
Two examples from Michael Moorcock's Elric stories:
The Weird of the White Wolf. Elric wounded Yrrkoon while fighting him. Yrrkoon starts laughing, indicating his sanity had broken.
The Stealer of Souls. When Elric finally catches up to him, Theleb K'aarna has lost his mind and is tittering to himself.
In "Dagon", the narrator begins giggling insanely after seeing the eponymous god.
In "The Call of Cthulhu", one of the two people who survives after seeing Cthulhu goes insane and laughs himself to death before they make it back to safety.
In Dan Abnett's Gaunt's Ghosts novel His Last Command, after they kill a Chaos stalker, Gaunt laughs and taunts the darkness with his still being alive. Ludd finds it more frightening than the stalker.
In a variant, there's a really nightmarish scene in The Odyssey where a character prophesizes the slaughter of Penelope's suitors by seeing them all racked with painful, hysterical laughter and choking up blood. And still continuing to laugh as they're slaughtered.
Vera Claythorne does this in And Then There Were None when she realizes U. N. Owen is enacting the bedtime rhyme and they're all gonna die.
A laugh burst from him. The terrified Angel caught him in her arms and tried to stifle the sound. She implored and commanded. When he was too worn to utter another sound, his eyes laughed silently.
In A Song of Ice and Fire, Catelyn Stark starts laughing hysterically after she witnesses her only remaining child Robb get stabbed through the chest.
In Ruth Frances Long's The Treachery of Beautiful Things, when Jenny definitively realizes she's in Fairyland and Jack tells her that no one will believe her, Jenny starts this. She doesn't realize it's her own for a moment after the first laugh, and it lasts a good long time. Since her brother had been swallowed up by the woods before her, she knows she won't be believed, quite thoroughly.
Live Action TV
Colin Baker's Doctor Who went a little bit nutty after his regeneration. This was meant as a return the character's dangerous unpredictability.
After his venture into the Time Vortex, Dalek Caan becomes the first "pure" Dalek to laugh.
And reused over in "The End Of Time" regarding the Master. All six billion of them.
Battlestar Galactica. Fisk, XO of the Pegasus, has a disturbing laugh that he gives after relating how Admiral Cain executed his predecessor. Fisk gives another such outburst in "Resurrection Ship", earning himself a puzzled look from everyone in CIC, who are unaware that Cain had just cancelled her orders to terminate them all.
Although any number of inmates in Oz (such as Tobias Beecher) would qualify, probably the best example would be former prison guard Clayton Hughes after he goes insane and murders an inmate. Particularly disturbing when it happens in front of Warden Glynn, who regards him as a surrogate son.
Happens to John a bunch in Farscape as a result of all the mindscrewing. His tendency to inappropriate laughter is a big part of what clues his shipmates in on his Sanity Slippage throughout season 2.
Avon from Blake's 7. In the season 4 episode Gold, upon realizing that he and his crew had not only accomplished nothing in the episode itself despite risking their lives repeatedly, but had actually benefited the villainess, he begins to laugh hysterically under the frightened stares of the crew.
Adrian Monk in the Monk episode "Mr. Monk and the Garbage Strike" briefly went laughing mad after deciding to dump garbage trucks overflowing with garbage into the San Francisco Bay one at a time, and coming up with an insane theory about who murdered the Garbage Union Leader (it being the rock star Alice Cooper over envy over a chair) that was moreorless done due to the piling garbage driving Monk completely insane, in addition to his previous theory being wrong (and for the record, the debunked theory was actually a lot closer to being correct compared to the second theory.).
Chang on Community. The study group refuses to let him join even after he dances for five hours representing them in the pop and lock contest. He ends up collapsing to the floor laughing maniacally.
In Sister Sister, Lisa Landry was breaking out into a fit of laughter during a funeral. It's justified, however, as just beforehand, she went to the dentist, and was exposed to a large, almost lethal dose of Laughing Gas due to the dentist ranting about the person the funeral was for.
Season 4 of Breaking BadWalt's reaction when Skyler tells him she gave Ted the $600,000 they needed to escape Gus, who said he would kill them all if he interfered in tipping off the DEA about the hit on Hank... which Saul had done on his orders mere minutes before.
In the movie Kamen Rider Double Returns: Kamen Rider Eternal, the villain of the movie tries to emotionally break Katsumi Daido, the eponymous rider. It worked a little bit too well, as Katsumi breaks down in insane laughter, followed by a Curb-Stomp Battle with the villain on the receiving end.
Buffy the Vampire Slayer. In "Prophecy Girl" Buffy has a mild episode of very unsettling laughter after she overhears Giles talking about her upcoming prophesied death. Played straight with characters who are insane: Masie the invisible girl, Mad Oracle vampire Drusilla, and Spike at the beginning of Season 7.
99:You're mad! Dr Poston: Mad, am I??? MAAAD AM I??? MWAHAHAHAAA!!! 99:(anxiously) Don't do that! Dr Poston:(utterly straightfaced) Don't do what?
Columbo has some murderers do this after Columbo figures them out. The most notable cases are Roger Stanford who cracked after Columbo tells him that he doesn't have the real cigarette box and Nicholas Frame who giggles and mutters a piece of monologue from Macbeth.
Just before the first guitar solo in the Thin Lizzy track "Chinatown".
"Inside the Fire" by Disturbed does this while combining it with the Evil Laugh; the character in which the song is being described to is most definitely going insane, but the main narrative is being told by his dead girlfriend whispering over his shoulder (who may or may not be The Devil). In other words, it's meant to sound both crazed and demonic.
Twilightning's "Rolling Heads" from the Bedlam EP ends with mad laughter.
Heard in the end of Running Wild's "Diamonds of the Black Chest" when after a lifetime of searching, the song's protagonist finds the eponymous chest. And it's empty.
Napoleon XIV's "They're Coming to Take Me Away, Ha-Haaa!" It's right there in the title.
The Bonzo Dog Band did a cover of "Monster Mash" that was pretty faithful to the original, until the ending, where vocalist Vivian Stanshall goees into an Evil Laugh that grows more and more manic through the fade-out.
"Departure", the Graeme Edge poem that opens The Moody Blues' "Ride My See-Saw", has Edge dissolving into mad laughter as it crossfades into the latter track.
Pink Floyd's "Brain Damage". (The lunatic is on the grass...)
The Police's "Mother," about a man whose overprotective, constantly-phoning mother has driven him mad, ends with manic cries that turn into laughter.
Doctor Steel can be heard engaging in a mad laugh near the end of his self-titled song, "Dr. Steel."
Ozzy is quite notorious for this, to the point where many a song of his features it. It's practically his trademark.
Arthur Brown does this a bit near the end of "Fire" as he's shouting "Burn!" over and over at the top of his lungs.
In one version of "Beginning to look a lot like Christmas", the second chorus of 'and mom and dad can hardly wait for school to start again' is immediately followed by the female backup singers doing a not quite sane laugh justlike the parents finally snapping due to holiday stress.
Eben Brooks engages in one of these at the end of his filk "Hey There Cthulhu" as the narrator finally succumbs to madness. It ends with a bloodcurdling scream as he apparently succumbs to something far worse.
In the Dangan Ronpa/Rabbit Doubt hybrid Doubt Academy, Akari Kagome, the Super High School Level Hockey Player, has one of these when she realizes she's going to be executed for a murder she didn't commit
In Exalted, Adorjan the Silent Wind is considered the Yozi patron of Ax-Crazy. As a result, her chosen Infernals tend to get access to Charms that reflect this, such as Broken Silence Laughter Defense (which allows the Infernal to throw off attempts to influence them by laughing inappropriately) and Eloquence in Unspoken Words (which gives the Infernal telepathic communication, at the price that they can only vocalize laughter).
Shakespeare uses this one in Titus Andronicus: Titus' daughter has been raped and mutilated, his sons have been accused of the crime, and he's been told they'll be pardoned if he just chops off his hand, so he does, and when he's given his hand back along with their severed heads, he begins to laugh. And plot tasty, tasty revenge.
Street Fighter has several. Vega, Adon, and Juri are probably some of the best examples. All three aren't exactly mentally stable and tend to let out insane laughs while fighting.
Shadow the Hedgehog ends several of his stories with an insane and/or evil laugh, including the ones where he plans to destroy the world and when he plans to take over the Black Arms empire.
Eggman is this in the pre-final boss cutscene in Sonic Generations. Lampshaded by Classic Eggman. "Wow, will I really get that crazy?"
Albedo in Xenosaga. His first freak-out, back in the past, involves him interfacing with U-DO and laughing like a maniac. Considering he looks about nine years old at the time, this is profoundly disturbing.
Or that he's laughing while ripping himself apart.
Ace Attorney:Phoenix Wright has quite a number of these, including: Damon Gant, Luke Atmey and Richard Wellington . Apollo Justice has Kristoph Gavin ,Ace Attorney investigations: Miles Edgeworth has Calisto Yew/Shih-na, with Yew's signature laugh cluing Edgeworth to conclude that she and Shih-na were the same person, and Dual Destinies has Ted Tonate.
The first sign that Alex's hold on reality in Eternal Darkness may be none too steady is the way her sobs when she first sees her grandfather's dead body are shot through with thin veins of laughter.
Maximillian Roivas hits this trope for brief intervals in his monster autopsy narrations, as well.
Daniella from Haunting Ground. She does this in cutscenes in a very creepy manner and at a certain stage of insanity while chasing you.
Fiona too, in the worst ending
Porky Minch seemingly loses his mind in the final battle of Earthbound, blithely releasing the lock on Giygas (purportedly his 'boss'). This renders Giygas unable to stem the tide of his power, which threatens to consume the entire universe. Porky addresses the player to admit he's afraid. And laughs.
In the direct sequel MOTHER 3, the team confronts a decrepit version of Porky, who has sent his robotic minion to bring forth the Dark Dragon. Until this point, it's unclear whether or not he realizes what the Dark Dragon — a genie who fulfills the wishes of whoever summons it — will do if that summoner literally has no heart. Turns out, Porky has gradually come to the same conclusion:
""If the dragon wakes up, it might end up destroying everything and extinguishing all life. Even so ............ahaha aha ahahahahahaha!!"
Lampshaded two times in Final Fantasy X, first when Tidus and Yuna talk about the importance of being happy and burst onto a cheery, loud laughter with no apparent reason. When they turn around they see all others staring them with a weird look on their faces. When questioned, Wakka quietly says: "We thought that you lost your minds." Done second time in Thunder Planes, where Rikku - who's deathly afraid of thunder - keep laughing nervously as they walk, prompting Tidus to comment on it: "Heh heh, heh. You're giving me the creeps!"
Kuja in Final Fantasy IX went Laughing Mad as soon as he learns from Garland's disembodied spirit that he'll die soon.
One of the first signs that Sephiroth went mad upon learning about his supposedly being the last Ancient is chuckling dementedly as Cloud/Zack entered the lab he was researching inside.
In The Legend of Zelda: The Wind Waker, Ganondorf (who has been surprisingly calm throughout the game) is about to wish on the Triforce, and King Daphnes touches it moments before he can, wishing for Hyrule to be washed away forever. Ganon snaps, spending a good thirty seconds laughing as water falls down around him.
Adam the Clown in Dead Rising laughs all the way through his monologue when he recalls his audience being eaten by zombies.
After bring defeated, he laughs and falls. Onto his still running chainsaws. The laughter doesn't stop until he's dead...
And it doesn't just get weaker and weaker. It gets deeper and slower.
Brent "Slappy" Ernst of Dead Rising 2 also engages in this during his boss fight, such as when performing a fire spin and/or shouting things like "I'm a little teapot!"
Very well done with Laughing Octopus in Metal Gear Solid 4. Since she was mind raped and turned into a psychopathic killer as a teenage girl, she never stopped laughing, even though her memories were constantly torturing her. She laughs throughout the entire boss fight and falls down laughing when she is fataly shot, making her a quite creepy encounter and not funny at all.
At one very brief moment of relative clarity before dying she even mentions "No, nothing is funny. I shouldn't be laughing."
Ed of Meryl's Rat Patrol 1 group, after the SOP system was locked down due to it refusing Liquid's DNA, went Laughing Mad.
Actually, any soldier who is hit with the laughing emotive ammo will undergo symptoms of Laughing Mad.
Raiden goes through this in Metal Gear Rising: Revengeance after embracing his Jack the Ripper persona prior to his battle with Monsoon. To see the previously calm and collected Raiden gleefully chop apart three enemy cyborgs after turning off his pain inhibitors is nothing short of chilling.
Take the definition of this trope, then apply it to Dancing Mad, then apply it to Kefka's character overall. Feel that? That's the awesome sinking in. It's also the closest thing to officially-stated motivation Kefka has.
It is also implied in Dissidia that his maniacal laughter is also really the only thing he could give as a reaction in regards to several things, regardless of what emotion he was actually feeling. For instance, when Kefka is defeated in Shade Impulse and explodes after giving his nihilistic speech, he can be heard laughing, but not a joyous laugh, a sorrowful one, and Firion mentions in his opening quote that he's never heard "a sadder laugh."
Ripper Roo from Crash Bandicoot after being exposed to different experiments from Dr. Cortex became a raving, laughing, lunatic in fact after his brain was tampered with all of his dialogue consists of insane laughter with subtitles to translate.
Father Grigori, the Zombie-slaughtering Badass Preacher of Half-Life 2 often breaks down into short bursts of maniacal laughter due to him being driven to insanity after the citizens of Ravenholm have become zombies.
Queen Zeal from Chrono Trigger. Every time she shows up to challenge you, she's got a crazy laugh going, even well after you've destroyed the Mammon Machine and defeated her in her One-Winged Angel form.
Ganondorf from The Legend of Zelda gets quite a few Evil Laughs throughout the series, but his laughter just before the final boss fight in Wind Waker was definitely Laughing Mad.
Majora's Wrath from Majora's Mask qualifies a lot, given the fact that its insanity has just reached its peak.
BlazBlue showcases Jin Kisaragi's slow descent into madness, and once he finally finds Ragna the Bloodedge, he completely snaps and starts speaking to him in a rather disturbing manner. Then there's Arakune, who ends as many as half of his dialogues with raving Voice of the Legion laughter. Nu-13 doesn't seem like the laughing type, but has been known to cackle admirably on occasion. And then there's Terumi...goddamn. All in all, the BlazBlue world could probably do with sedatives in the water supply.
Zero from the Mega Man X series (while he was still a Maverick) also had bouts of the trope, made especially apparent when he was beating Sigma to a bloody pulp when the latter was at his mercy.
A few times during Metroid Prime 2: Echoes, Dark Samus often starts breaking into maniacal laughter. Similarly, in Metroid Prime 3: Corruption, after Gandrayda, while disguised as a GF Trooper, attempted to shoot Samus in the back and missed, started going into a fit of hysterical laughter.
In Cave Story's Bonus Dungeon, the boss Ballos states that when his magic went wild and he killed everyone in the kingdom, he could only stand where he was and laugh.
In the anarch and independent endings of Vampire: The Masquerade – Bloodlines, Sebastian LaCroix gets down with the best of them when he realizes that the MacGuffin he just opened is not so much a 'gateway to infinite power' as a 'gateway to horrible burning pain' and he's been played for an Unwitting Pawn.
In killer7, the first indication of an approaching enemy is always a little insane giggle. If you're too slow with your gun, it's followed by a shrieking laugh as they blow up in your face.
In Suikoden II, the main villain, Luca Blight is known to often punctuate his horrific actions with a horse like Evil Laugh. However, when he is finally near death, he lets out a speal of insane laughter filling up more than 3 dialogue boxes that can't be classified as anything but this.
Bobby Barrows, aka "Scissorman" in Clock Tower often seems to giggle. In fact, the first sign that he is nearby is that he cackles.
In Super Paper Mario, a Sammer Guy, appropriately named Laughing X-Naut, laughs a long, loud laugh as the Void in his dimension fully matures, destroying his entire universe. He laughs all the way until his inevitable annihilation.
Siarnaq:NEXT OBJECTIVE: CONTROL CENTRAL OF LEGION HEADQUARTERS. Hihi- Hihahahaha!
An update for Jojos Bizarre Adventure All Star Battle added laughing taunts for the characters who fought the Sun stand during Part 3. Certainly seeing Jotaro and Kakyoin laugh hysterically at how pathetic you are must be very unsettling...
In the Ace Attorney series, Luke Atmey and Kristoph Gavin laugh disturbingly upon defeat, possibly to indicate madness (they're both pretty crazy). Damon Gant gets the most epic one, however: he claps as he laughs, and as the laugh revs up, his hands slam together so quickly they throw off sparks!
The tradition continues in Ace Attorney Investigations, where the killer of case four, Kazura Himiko/Calisto Yew ends up doubled over laughing by the time he/she is done... and then shows just how sane she is by pointing out Edgeworth just accused her of murder... in a case where one of the pistols is still missing. And then case five happens and holy hell is Shih-na's breakdown some quality horror.
Non-villainous example is Lotta Hart from Justice For all. She thinks that the crime scene will be her one big break and starts laughing crazily as she runs to it. Even Phoenix got scared when that happened.
According to the story hidden in the filenames of Narbonic, this is how Helen went mad:
She laughed hysterically for a minute or so. Not a good sign, she thought. And then the thought fluttered away. Her face, when it skipped into focus, was pale and blotchy. Possibly she had been crying. Yes, someone had definitely been crying sometime. Not her. Not when everything was so funny and she had so many interesting ideas...
Ellen in El Goonish Shive does one of this, complete with a line that goes behind a character's head to show they've snapped when she is first brought into existence, and she thinks that she'll die in a month. The comic title says it all.
Dr. Horrible starts out maniacal laughing because he's Genre Savvy, and then does the laugh again because it's situationally appropriate. Even though we see his Sanity Slippage happening immediately in the next song... we never see him laugh again. It's almost like he went sane.
Everyman HYBRID, "Joke's Over" Evan, when he sees what's inside the garbage bags hung up by the Slender Man. He hasn't completely snapped yet, but he's definitely getting there.
At the end of his review of The Neverending Story 3, The Nostalgia Critic starts laughing nonstop as he leaves his house, drives to an Home Depot to pick up a crowbar, and heads back home. He stops laughing when he smashes up the DVD, AVGN-style.
He does it again in the Master of Disguise review, where he responds to a "funny" joke by flipping out, laughing insanely, and beating three people with a baseball bat.
...Where was I for the last two minutes?
One Hundred Yard Stare: Ellie goes laughing mad for a moment in episode five. And later several times, also this is her basic mode in season two.
In The Spectacular Spider-Man, when Harry Osborn thinks that he was blacking out and becoming the Green Goblin, one of his many reactions, besides depression and anger, is semi-maniacal chuckling.
Another Spiderman Example. In fact, another Harry Osborn example. In the 90's Spiderman show, when Harry finds out that The Green Goblin was his father, he goes into a laughing fit (his mind wasn't too stable at the moment, he was talking to his father's ethereal head from another dimension and all that... long story...) and then decides to "fulfill his destiny" and become the second Goblin.
Most extreme cases include when he was under the effects of the happy helmet (complete with a full set of grimaces), and when he was beating George Liquor up with an oar in a banned episode, "Man's Best Friend".
At the end of Batman Beyond's first episode, when Corrupt Corporate Executive Derek Powers sees that he has transformed into a glow-in-the-dark radioactive skeleton man, his immediate reaction is to begin laughing maniacally. The doctors are appropriately freaked out.
Coincidentally, he reacted to his new appearance in a manner that is eerily similar to the Joker from the 1989 Batman film under eerily similar circumstances.
In "Cleanliness is Next to Edness", Edd goes insane after failing to find a place to bathe and getting dirtier with every attempt. He snaps out of it, eventually.
Lisa Simpson briefly went Laughing Mad when seeing her new braces in the episode Last Exit To Springfield, of which it was a direct homage to Jack Napier's reaction to his new appearance due to botched reconstructive surgery and falling into the vat of chemicals.
When Sideshow Bob ran for mayor and won, he burst into a maniacal laugh.
Hexadecimal from ReBoot enjoys her evil laughter, but, being pretty crazy, she tends towards Laughing Mad on more than one occasion. Then she becomes outright insane in season 3, due to a combination of being nearly destroyed in an explosion and subsequently rebuilt, her mask becoming cracked, and being tortured and used as a weapon by Megabyte. After this, pretty much every time she laughs is an example of Laughing Mad. (At least, until Bob defragments her head.)
In Family Guy Meg is sometimes portrayed as deranged or disturbed out of a desperation for love and attention. In one scene Chris asks her what kind of gifts boys have gotten for her and she describes imaginary gifts given to her by her imaginary boyfriend prince William before laughing crazily and running out of the room in tears.
In Adventure Time, we have Lemongrab's utterly disturbing laughing fit in Too Young. He doesn't even SMILE- his head just flails around and bounces with weird squishy noises, and his eyes are wide.
Lemongrab: "...Prank? F-for laughs? Yes, of course; just a harmless prank... F..for laughs... Ha..a.a? HAHAHAHAHHAHAHAHAH-OH! HAHHAHOAHAOHAOAHOAHAOAHAHAOAOAAHAOAHAOAHAOA-" *immediately returns to normal* "Twelve years dungeon! All of you- DUNGEON! Seven years, no trials! C'mon... LET'S MOVE IT!!!"
He comes by it honestly; his mother Princess Bubblegum reacted similarly to the prospect of Finn bringing the Duke of Nuts to justice. "The justice... of a COLD DUNGEON! MWAHAHAHA-AHAHAHAHAAHAAA!!!" Jake Lampshades the moment by saying with an awkward laugh, "She's completely bonkers."
In Teen Titans "Nevermore" when Robin and Starfire go onto the roof of Titans Tower to tell Raven about her door being broken down, she breaks out into hysterical laughter which sounds just like something out of Higurashi no Naku Koro ni, then she just abruptly stops and goes inside.
In Wakfu season 2 episode 20, Qilby goes completely nuts after merging with the Eliacube and laughs maniacally during his Teleport Spam at the tail-end of his fight with Adamai.
Played completely straight in the infamous Hercules / Aladdin: The Series crossover episode "Hercules and the Arabian Nights", however: Shortly after Jafar is revived by Hades, he starts using his cane to cause huge amounts of destruction in Hades' lair, while laughing maniacally, causing Hades to object and even go as far as to take away his cane (which is his only lifeline) to get him to obey.
The animated adaptation of Wyrd Sisters has Felmet going more and more insane, and as he slips further off the slippery slope he sure lets out a lot of maniacal laughing.
In the famous Milgram Experiment, which was meant to test how far normal people would go when obeying the orders of someone in a position of authority, one of the subjects, an encyclopedia salesman, went into fits of hysterical laughter when he heard the screams of pain from his supposed victims, to the point where the session had to be discontinued. He wasn't a sadist, or insane; the laughter was just an indicator of the extreme emotional stress he was under.
There's a condition called Pseudobulbar Affect, in which the patient loses the ability to regulate emotional expression. They may collapse into a sobbing heap at the sight of a kitten, show absolute terror at their loved ones or laugh hysterically and uncontrollably at the loss of something dear to them. This is involuntary.
According to legend, Nero was laughing while watching Rome burn, though we only have his enemies' word on this. It's unclear whether he was even in the city at the time.
John Lennon broke down into hysterical laughter upon hearing that his friend Stu Sutcliffe had died. He did the same thing after his mother had passed away.
Many people use laughter as a defense mechanism, in order to deal with some terrible thing.