Sasuke in Naruto has a massive one after finding out that Itachi killed their parents among many others, as well as when he gets put under Mind Rape. Arguably experienced a very controlled version when Madara revealed the cause of the Uchiha massacre, leading to Sasuke's new life goal.
Gaara suffered this twice in his life. The first time was when Yashamaru crushed all of Gaara's hopes and tried to kill him resulting in the homicidal maniac we all have vivid nightmares about. The second was when he saw his own blood after Sasuke injured him.
Naruto had one when he thought Sasuke had been killed by Haku, and an even worse one when he saw Pain, the man who had murdered his beloved mentor and blown up his village, stab Hinata with a giant spike just after she confessed her feelings. The Freak Out was of such proportions that it allowed him to skip immediately to the six-tail form and left his will to continue so battered he nearly knowingly released the Kyuubi.
And before that, he'd gone into his four-tailed form when Orochimaru goaded him to breaking point.
Poor, poor Obito. Survived from being crushed with boulder, he ends up watching Rin die in Kakashi's arms. Both of them are his best friends. No wonder he snapped... and that's how Madara/Tobi was born.
Nina in Code Geass puts the "psycho" back in Psycho Lesbian after the "Euphinator" incident late in the first season. When she sees how many people her FLEIJA warhead killed in R2, she makes a similar but slightly less appalling face.
Then there's Suzaku after Euphemia's death and Lelouch when he kills his father the first time.
Death Note: Light Yagami towards the end of the anime, as well as after L's funeral (where he crawls on top of L's grave and screams at it), and after talking to L for the first time and learning his name.
Also in the Grand Finale, Teru Mikami freaks out when he sees his god, Light, get arrested by Near, and starts makes crazy faces that outcrazy Nina's face above. In the anime, he even stabs himself in the heart with his pen and spews a fountain of blood until he dies.
Touta Matsuda also has one when he sees Light trying to write Near's name in a hidden death note and shoots his hand, goes into a rage and shoots him some more, and tries to deliver the killing blow but he is stopped.
Kish from Tokyo Mew Mew gets this way when Ichigo rejects him, or when someone else threatens to come between him and Ichigo.
School Days: Sekai, after Kotonoha and Makoto make out in front of her, and Kotonoha after she is raped by Makoto's best friend and then dumped by Makoto.
Keiichi from Higurashi no Naku Koro ni has a truly epic one in Tatarigoroshi-hen. He spends the majority of the arc having one of the most surreal experiences this side of David Lynch. When he finds out that he never killed Satoko's uncle, and he's been having paranoid delusions, he goes batshit crazy and tears up Satoko's house with a hatchet looking for him.
Except he really did kill Satoko's uncle. He only believes that he's still alive because Satoko told him that he was, not realizing that Satoko is approaching a mental breakdown of her own. The one who has a true Freak Out is Satoko herself, when she thinks Keiichi killed Rika. She ends up pushing him off a bridge.
As this is a series known almost famously for its levels of Break the Cutie, several of the main characters go through one of these at least once, in at least one arc. Keiichi, then Shion, then Satoko and Keiichi, then Rena in the Atonement Arc, mirroring Keiichi's first, it gets to the point where we learn that even Takano Miyo, the cause of Rika's repeated deaths, actually had one or more of these as a child, preluding the entire series and showing the reason for her villainous tendencies.
This trope was perfected by the anime Paranoia Agent, where the entire theme of the show was about nervous breakdowns. Whenever the show had a Freak Out, it would get deep inside the head of the victim, and about half the episodes ended with The Reveal that the victim had badly misunderstood the traumatic event.
Although we don't see it onscreen, Maniwa presumably has one of these after being fired, as the next time we see him he's gone from a reasonably open-minded good cop archetype to a delusional homeless person who believes he is a Super Hero.
Smoothly and successfully executed in Yu-Gi-Oh! GX in the case of Kaiser Ryo's transformation to "Hell Kaiser."
Elfen Lied: Happens on numerous occasions to several characters. Most notable are Kouta after witnessing his sister and father being slaughtered in front of him by Lucy; happens again later on after he starts to remember bits and pieces of his traumatic past, and again when he sees Lucy slaughter people in front of him. Lucy during the event where a particularly nasty group of bulliesKick the Dog that she had come to care for and beat it to death, forcing her to watch. Mayu after running away from home because of her stepfather's sexual abuse and her mother's refusal to believe that her own daughter is being raped because she's jealous of her. Mayu gets another in the manga when she's about to get raped by The Unknown Man, which is directly related to the aforementioned abuse.
Suzu after being raped in Peacemaker Kurogane and as soon as he finds his master lying motionless and in pieces on the ground, supposedly killed by his (best and only friend) Tetsunosuke. Ouch. Even though Okita was the one who killed Yoshida. Also, Tetsunosuke has massive freak outs throughout the series, most notably after Yoshida attempts to kill him a second time.
Akito from Fruits Basket often has violent, screaming fits on the least provocation.
SHUFFLE!: Kaede, after finding out that her mother died and after Rin starts spending more time with Asa.
Fullmetal Alchemist: Ed has at least one of these, most notably when he saw the failed attempt at resurrecting his mother as a child.
Greedling suffers one after he encounters the last surviving loyal chimera henchman of the previous Greed lurking under CentCom. He kills the chimera, and then the memories of the previous Greed all come rushing back.
Perfect Blue: Mima, coming home at the end of a particular traumatic day, finds her beloved pet fish dead, and loses control for a moment, trashing her apartment. The trauma was because of a rape scene, which may or may not have become genuine, as her screams got more and more convincing. She, as well as Rumi have numerous moments where they Freak Out throughout the rest of the movie.
Ken in Digimon Adventure 02 had two. The first was a nervous breakdown when he realized the sins he'd committed were real — further increased by his partner dying, which brought back all his repressed memories of his brother's death. The second was during when he found himself at the Dark Ocean again.
Hikari had one, also when she returned to the black ocean, that she needed to be slapped out of it in a very Get a Hold of Yourself, Man! moment.
In the manga version of Chrono Crusade, it's revealed in a flashback that Aion had one of these after finding out that his mother was a human transformed into a demon, and she was pregnant with him and Chrono when it happened. It appears to be one of his underlying motivations for almost all of his actions in the series.
Axis Powers Hetalia suggests that Russia became Cute and Psycho after Bloody Sunday. Fandom speculation is that the execution of the Romanov dynasty is what drove him completely over the edge.
In a flashback of Muhyo And Roji, Enchu is introduced as working hard to become an Executor to support his sick mother. He is called away when his mother's condition turns critical, and while he is away, she dies and Muhyo is chosen as Executor over him. In another flashback, this happens to a mother when her daughter dies in a car accident; she becomes obsessed with making copies of the doll that her daughter had wanted.
In YuYu Hakusho, Sensui has one in the past after finding out about humans torturing demons, which challenged his belief that demons were evil and that he should protect humanity from them.
Her most extreme case was when she was forced to scry, learned the person she was talking to was a shapeshifter, then saw his impending death. The moment she saw his body crushed in her mind, she freaked out so badly she went into cardiac arrest and had to be saved with chest compressions.
Johan has one of these after reading a picture book.
Faust VIII from Shaman King is usually calm (being a doctor), but when Yoh Asakura calls Faust's beloved Eliza (Eliza was Faust's wife who was brutally shot and killed, and now is Faust's spirit) a doll, he goes apeshit!
For 21 episodes of Lucky Channel, Minoru Shiraishi calmly endures the constant abuse and disrespect of his diva of a co-star, Akira Kogami. Then he gets roped into trekking two weeks through the wilderness to retrieve a fresh bottle of spring water for her, getting mauled by a bear in the process. When he returns to find himself replaced as co-star by Daisuke Ono and then has Akira throw the water back in his face for being too warm, he goes completely berserk. He tells off Akira, trashes the set, clobbers crew members who try to restrain him, attacks the cameraman, and is last seen chasing Akira off-stage with presumably murderous intent. He eventually calms down, but in the concluding episode he is a completely different character, much less overtly cheerful and with a bitter, cynical inside.
As aside, one can't help noting that his interactions with Akira in that last episode resemble the early phases of a Belligerent Sexual Tension plotline. The series ends before this can be explored very deeply. About damn time. For both the freakout, and the Sexual Tension.
Darcia from Wolf's Rain's bloody self-mutilation and Skyward Scream upon coming home to find that his lover, Hamona, has been murdered.
In Fairy Tail, Elfman and Mirajane both went through one of these around two or three years before the start of the series due to the death of their youngest sibling, Lisanna. The former turned from a Nice Guy, domestic, overprotective crybaby kind of guy to a super MANLY... nice, domestic, overprotective secretly crybaby kind of guy. The latter turned from an Arrogant Kung-Fu Guy delinquentish character into Silk Hiding Steel.
Sting also has one when his guild master kills his cat companion and best friend Lector right in front of him. That he's scolded by Jienma for being appropriately upset doesn't help to prevent him from snapping.
Space Battleship Yamato. The scriptwriters love making Desslok freak. In season one, his home planet is Curb Stomped and he freaks. In The New Journey, his planet is utterly destroyed, so he freaks. Then his love interest kills herself. He completely loses it and begs Wildstar to destroy his ship.
Black Butler II episode 10. It begins with Hannah talking to Ciel and saying that she has something to show him. Then her mouth opens unnaturally wide to reveal this black abyss where the inside of a human mouth would be. The eye she stole from Alois Trancy is rooted in the back of her throat, and since Ciel's soul has been partially fused with Alois's at this point, he's staring at himself from inside her. Hannah watches calmly while Ciel suffers a severe nervous breakdown and screams before falling unconscious.
In Deadman Wonderland Ganta does this understandably as he's being forced to watch the Carnival of Corpses. Later, Rokuro has a massive one when his calculations were destroyed. In the dub, however, he was mad because he thought the had found of out about his bomb, and the fact that they were still alive.
Pandora Hearts: Leo's reaction to Elliot's death had a lot of sobbing and screaming. He went on with this as Pandora was interrogating him until Vincent came along.
Bird's Nest from Copernicus Breathing has several of these, most notably when Mina (intentionally) falls off of the trapeze, which reminds him of the death of his younger brother. Other times this has happened were when he hears news of Leo's juggling accident and when Michel finds his stash of drugs and attempts to take them away.
In A Cruel God Reigns Jeremy has almost too many of these to keep track of. Some good examples are when Ian grabs his arm while trying to ease him out of his Heroic BSODDumb Struck, Ian asks who Valentine is after Greg does something very unpleasant with the wooden egg she gave Jeremy, and when Ian finds Jeremy taking heroin after being sexually assaulted at school in Boston. His other major episode is when he hallucinate Greg is following after he and Ian go over all of his Embarrassing Old Photos.
Nui Harime from Kill la Kill goes through a major one in episode 22 when Ryuko permanently destroys her arms, shocking her, and causing her cheery personality to become psychotically angry and vengeful. However this is subverted in the next episode when Ragyo gives her replacement arms and she calms down a bit.
Rorschach from Watchmen, despite coming from an absuive background, seemed to have a good head on his shoulders until he investigated the disappearance of a girl who turned out to have been murdered and cannibalized by her attacker. He then went Rambo-like insane and never went back.
Notice that in flashbacks set before his Freak Out, Rorschach has a normal speech bubble. After the Freak Out, his speech bubble is more scrawly. That's how cuckoo he has become.
The Joker is a firm believer in this trope, once saying that all it takes to separate the sane from maniacs such as himself is "one bad day." The Killing Joke storyline features him trying to give Commissioner Gordon his Bad Day.
Batman is the poster comic of Freak Outs, with most Rogues' minds breaking at some point, creating the other selves which drive Batman's duality theme close to home.
Virtually every member of his rogues gallery can have their defining transformation into villainy traced back to a single traumatizing event. Acid in the face, mutations, murdered parents, rescued parents, murdered spouse, etc.
When Green Lantern Hal Jordan suddenly lost his marbles and became the universe-destroying maniac Parallax in the 1990's, after his home city was destroyed by a supervillain. Years later, it was later retconned that Hal was merely possessed by a giant yellow ancientembodiment-of-fear bug monster, and not evil after all. Um, sure, okay.
Hank Pym, of The Avengers, had a period where he thought he was someone else, and apparently went full on mad scientist, to the point of setting killer robots on a major city just so he could destroy them to look good. He eventually recovered, and how much this gets played up depends on the writer. Some have him as having become fairly well adjusted, others have him just a medication bottle away from another psychotic episode. And then there's Secret Invasion.
Happens to Nuke from the Squadron Supreme after his parents died from radiation poisoning. Then again, he was probably not too stable to begin with, given that his attempt to solve the problem was asking a teammate to find a cure for cancer...
X-23 naturally isn't normally prone to these, but even she has one (or at least, what passes as one for her) when she wakes up in a Weapon X facility after Kitty Pryde and the O5 find her wandering the streets of Miami in an amnesiac state following the events of Avengers Arena and having been tortured by Purifiers after that. She immediately panics and rampages through the place seeking a means of escape, before Teen!Scott manages to calm her with a Cool Down Hug.
Spider-Man has had plenty, thanks to his "Parker luck". The most infamous example probably being Gwen Stacy's death.
Happens to Kerrun, the Raleka leader, at the end of her Villainous Breakdown in With Strings Attached. She wasn't too stable to begin with, and the seeds are sown when she first realizes that the four are not on her side, as she'd originally thought. What really sends her over the cliff is when John is seen flying over the warehouse, having lured hundreds of skahs there. She completely cracks, screaming that all the skahs are actually Idris and that the Raleka should kill them all, and John if he reappears. This has the unintended effect of getting all the Raleka guarding the warehouse to focus on the skahs, who after all are mobbing the outside of the warehouse, and not to keep an eye out for John and Ringo, who are lurking about trying to sneak into the warehouse via the roof.
In Bitter Leaves and Blossoms Bright, Isra has a delayed and subtle one after her first (and very messy) kill. When Altair tells her It Gets Easier she holds on to him shaking and as it sinks in.
In the novelization Palpatine takes time after Windu's death to guide Anakin in a Sith technique that lets him separate from his emotions and calmly dissect them. Anakin uses it to crush his own fear, which has the bonus effect of turning him into The Sociopath. By the time he snaps out of it he's gone well past the Moral Event Horizon and killed or alienated everything worth turning back for.
Mousy secretary Selina Kyle from Batman Returns, after almost being killed by her boss Max Shreck for knowing too much about a power plant that will ultimately hurt Gotham City, is in a very bad way. After being revived by her cat Miss Kitty and all of her feline friends, Selina returns to her apartment, repeating the words she said the last time she was there in a Creepy Monotone, and just manages to hold herself together until an ad on her answering machine that mentions "a candlelight staff meeting for two" with her boss proves to be the final straw that pushes Selina over the edge and drives her to trash her apartment and become the dark and dangerous Catwoman.
The Descent. A year after being in a car crash that killed her husband and daughter [which itself caused a Freak Out] Sarah goes on a caving trip with her friends. Then they get trapped down there. Then monsters arrive. Then she ends up alone and hiding about two feet from a group of monsters eating one of the other girls. Her long due full blown Freak Out occurs when she grants her best friend's I Cannot Self-Terminate request, and she becomes a killing machine unable to feel emotions except for hate and bloodlust. By the end, she's so crazy that she murders one of her other friends, then hallucinates that either her daughter or her murdered friend is right beside her, depending which version of the ending you're watching. Interestingly, Juno waffles back and forth on this trope. Alone, she starts down the same path as Sarah on the bloodlusty killing machine bit, but this stops once she finds two of the other girls. They die - bloodlusty killing machine time. Sarah meets up with her, and for a minute Juno is normal again, but Sarah herself being a bloodlusty killing machine causes Juno to follow suit again before being murdered herself.
Harvey Dent suffers one of these after losing half his face in every version, but it's especially pronounced in The Dark Knight, where he spends two thirds of the film as the "White Knight" before losing half of his face to a bomb planted by the Joker and it's hinted that he sustained brain damage in the accident. The Breaking Speech afterwards exagerated it since he had lost his girlfriend Rachel in the same Sadistic Choice that led to his own scarring...
In Batman Begins while in prison, Falcone tries to blackmail Crane into allowing him a part in the upcoming fear toxin project. Crane instead gasses him with the fear toxin, causing him to have a screaming fit.
Harry Osborn, Norman Osborn, Eddie Brock, and Doc Ock have this happen in the Spider-Man movies. As well as Peter after he finds his uncle dead on the ground, and anytime a villain kidnaps Mary Jane and threatens to kill her.
Lon Chaney Sr. has a truly impressive one in the film The Unknown (1927). He plays Alonzo, a criminal fugitive who's hidden out at a circus disguised as an armless knife-thrower (he has his arms, but also a distinctive and identifiable hand deformity); Nanon (Crawford), the circus owner's daughter, has a distaste for being touched by men due to some past trauma and becomes friendly with him. As his love for her grows, he takes the next step and has both his arms amputated— just in time for her to get over it thanks to the circus' handsome strong man... (Probably also qualifies as a Villainous Breakdown, given how quickly things get worse.)
The infamous 'He's gonna pop' scene in The Matrix.
In Thor, Loki has an unstated but quite evident one after learning that he is a Jotun. He then goes from mean-spirited trickery to ruin his brother's reputation to trying to kill him in order to protect a self-loathing rife genocidal scheme against using all of Jotunheim destroy Jotunheim.
Ralphie from A Christmas Story. He had a bad enough day after failing to win over his teacher with his Red Rider BB Gun essay, but then he had his glasses busted by Scut Farkus. Rather than run away, as he did many times before, Ralphie snaps and starts beating the snot out of Farkus.
The title character of Carrie has a similar freak out to Ralphie, but the results are far more destructive: rather than simply beat the snot out of the bullies who poured pigs blood on her in front of the class, she burns the school down with everyone locked inside. This wasn't the first time she was bullied, but it was this moment that finally sent her over the edge.
Ivan's manic episode in The Brothers Karamazov took its time in developing. You can see him start to go insane from very early on in the book. It becomes obvious to us when he starts to talk to the devil. But he finally has his Freak Out moment at Dmitri's trial, when he confesses that he killed his father through Smerdyakov, who has conveniently committed suicide which would sound ridiculous even to us if we didn't know it was the truth. When the people in the courtroom voice further doubt, Ivan loses it. Spectacularly.
Done in Ender’s Game when Ender decided that if the people who run the games won't be fair, then he won't play the game.
Ender suffers an even worse freak-out at the end of the story when he realizes he's been tricked into committing mass genocide of an entire alien race.
In book 8 of The Pendragon Adventure, Bobby hears Twig say that they should go back to Ibara, which confuses him because he was on the territory of Ibara. This leads to him freaking out while asking why Twig said this. Ibara is the name of an island: the planet is Veelox, in the far future, and Bobby just realized how badly he's been played by the Big Bad.
In the Dexter series of novels, it is revealed that Dexter and his brother had their freak out early on, when they saw their mom killed with a chainsaw and were hiding partially submerged in blood for hours. Clearly this was a defining event for both of their lives.
Sgt. McCron from ''The Thin Red Line" suffers a nervous breakdown after all his men die in battle.
In the steampunk science-fiction novel The Woman Between The Worlds by F.Gwynplaine Macintyre, the narrator experiences horrifying encounters and wonders if he is insane, then realizes that only a sane man would question his own sanity. Near the end of the novel, the narrator no longer questions his sanity, not realizing that he has indeed become unbalanced by his ordeal.
Happens tragically to Xinemus in Second Apocalypse, as well as Achamian. The former becomes a broken shadow of his former self, while the latter is hardened by his ordeal.
Happens to Bryce in the Donald E. Westlake book, The Hook, where, after Wayne kills his wife Lucie, who he is going through a very long and bitter divorce with, in a deal to get Bryce to credit Wayne's (who can't get publishers to publish his work) manuscript to him and get half of the money. After the murder, Bryce begins to gradually go insane, kicked off by his love interest leaving him, and him becoming isolated in his house in Connecticut. He is unable to write anything but worthless nonsense. In an interview, all of his answers are complete nonsense. He becomes obsessed with how it was like to murder his wife, having constant dreams of violently murdering his wife, but being angered because he can never see here face, and wishes that he was the one that did it, even following a woman who wanted his autograph to her house and almost attempting to kill her. At the end, it is implied that he murders Wayne's wife Susan in the last passage of the book.
Bryce: The thing is, I just have to know what it was like, Lucie.
Susan: My name is Susan.
Bryce: Not anymore.
A Storm of Swords: Catelyn Stark has hers at the Red Wedding. With her husband executed, one of her daughters held a political hostage, the other missing, and two of her sons believed dead, Catelyn only really has Robb left as her family. Then Robb is killed by one of her turncoat bannerman. She starts laughing hysterically, claws at her face, and as her enemies move to slit her throat, all she can think is she hopes they don't cut her hair, as her husband loves her hair. The Freak Out then continues after she comes back from the dead...
Angel: Doyle didn't take the news of his demonic heritage well, and ended up boarding himself up in an apartment and chain-smoking all day.
iCarly: Carly is quite susceptible, most notably in iThink They Kissed and iSpace Out. Minor variations are the instances where she delivers long rants like in iSaw Him First and iDate a Bad Boy. Also, Mrs. Benson will freak out of anything, usually hauling Freddie off for a tick bath, like in iFence.
Every now and then, River Tam will have some sort of freak out, some worse than others. The one in Objects In Space takes the cake for the series (but the movie outdoes it) with her feeling some people's emotions and reading others' minds. This freak out also gave us many peoples favorite scene, River rubbing herself (though not there, If You Know What I Mean) while watching Zoe and Wash have sex.
On Ally McBeal, Billy started out as the straight man of the cast. Later, he suddenly dyed his hair blonde, and turned into a sexist, smug jerk (with an occasional flash of remorse). This was later explained as a brain tumor, which killed him.
If you're going to come back to your arch-nemesis' place with a gun, be careful where you point that thing...
Unless the last thing you want to hear before before being deprived of your epidermis is "Bored Now".
After the accidental killing of the deputy mayor, Faith reacts by becoming simply and utterly psychotically monsterous. After something of a reformation, she does it again after the death of her father figure. The second (and possibly the first) time is because she is attempting suicide by whomever she can anger enough into killing her.
Exemplified by Dark Willow. When Tara is gunned down in cold blood, Willow utterly loses it and in the space of the next 24 hours or so manages to kill Sunnydale's most powerful magic user, smack down the combined powers of the UK's strongest wiccans, effortlessly murder the season's Big Bad up to that point, beat the stuffing out of the Slayer, and nearly blow up the world.
Dawn has one after learning she's the Key.
Manny on Degrassi The Next Generation started out as a cute, giggly girl who acted about half her real age. In a single episode, she finally realized that people didn't take her seriously — and instantly transformed into a manipulative, sex-crazed attention hogger. She got worse.
Also Degrassi: Campbell completely breaks down in an anxiety attack in Say It Ain't So. Bianca finds him in a sobbing heap in the girls' bathroom which he didn't realize he had gone into until she calls him a stalker and he notices the tampon dispenser.
Every regeneration is a Freak Out in that it traumatically, completely and permanently changes the Doctor's personality and appearence, and catalyses and concludes whatever that particular Doctor's character development is. A few examples:
The Doctor dies from a combination of old age and Mondas's influence in "The Tenth Planet", and returns with a more mercurial but also quirkier personality and much, much better social skills. The 'change' process is apparently very traumatic (production documents reveal he was reliving all of his past traumatic memories during the process) and it takes him quite a while to come to terms with who he now is.
The Third Doctor spent his life exiled to Earth by the Time Lords and working as an agent in a Mildly Military setting, his personal philosophy placing a great deal in loyalty and authority. His death of radiation poisoning transformed him into a manic, crazy-eyed Cloud Cuckoo LanderMan Child who absolutely could not stand taking orders from anyone and would happily burn all authority to the ground if he could, with the implication that this was suppressed rage from his initial imprisonment finally breaking into his personality. In addition to this, he became detached and aloof around people he'd previously thought of as his best friends and even tried to suddenly abandon Sarah Jane so he could travel on his own, though this was done out of confusion rather than apathy and he gave her a jelly baby as an apology later.
The Fifth Doctor had a fairly rough time of it as an incarnation anyway, but "The Caves of Androzani" is pretty much about torturing him to death. The experience forced him to make awful decisions, and as he began to regenerate he had hallucinations of the Master taunting him - the poisoning was bad enough that he almost died for real during the regeneration. The result of this was that the Sixth Doctor was a lot less mentally stable than the Fifth, with a difficult, sadistic and insane personality, experiencing strong feelings of painful body dysphoria. He even attempted to strangle his companion due to a delusion that she was evil.
The Seventh Doctor freaked out prior to becoming the Eighth, but for different reasons. He regenerated because the doctor trying to save his life was actually killing him due to her ignorance of his alien physiology. The Eighth Doctor, while more stable than the Sixth, also was a rather mentally flaky incarnation, being particularly prone to amnesia and detachment from reality.
During the transition from his Tenth to Eleventh incarnation, the Doctor was extremely reluctant and panicked when undergoing the regeneration process. The eventual energy release blew apart portions of the TARDIS bridge.
Over the course of a single episode full of Time Skips the Eleventh Doctor aged 900 years - over The Slow Path - on Trenzalore while trying to stop the Time Lords coming through into the universe. Immediately after regenerating, in "Deep Breath", he takes on a much more aggressive and commanding personality and tells Clara he's abandoned his interest in being her 'boyfriend' or acting like a human.
Lesterson from "The Power of the Daleks" lost his marbles when he learned that the Doctor was right about the Daleks all along.
The K1 in "Robot" was just about holding onto sanity until it killed its 'father' in self-defence, after which it snapped and started trying to start a nuclear holocaust to wipe out all of humanity apart from Sarah Jane.
The Tenth Doctor had a huge one in "The Waters of Mars", where he basically snaps after refusing to accept that a group of good people have to die just because history says so and basically turns into his archnemesis the Master briefly. This affects him for the rest of his run. That entire segment can basically be summed up in this line:
THE LAWS OF TIME ARE MINE! AND THEY WILL OBEY ME!"
In Hannibal, Will Graham has one when he wakes up in Dr. Lecter's office, with his last memory of standing on a beach at a crime scene in West Virginia. He understandably starts to panic, realizing that he was out of it for nearly four hours.
Ryan on the US The Office in the season 5. After years of working at the surreal Dunder Mifflin, constant sexual harassment from Michael Scott, the horror of actually having a relationship with the vapid Kelly, getting promoted during a recession, getting addicted to cocaine (Truth in Television - it turns you into an asshole), running a massive fraud, and getting busted and fired, then starting all over again as a temp at Dunder Miflin, Ryan now carries a notebook filled with the names of people who piss him off. So he can "get back on them once I'm on the top again".
In the last season of Battlestar Galactica, Felix Gaeta loses it big time after fellow Bridge Bunny Dee shoots herself dead, being unable to cope with the consequences of the latest Wham Episode. It had actually been building for some time, but the change in his demeanor and attitude after this particular incident was quite drastic. Getting shot in the leg by Anders and then losing said leg didn't help much either, nor did finding out that the afforementioned Anders and the XO are Cylons and discovering that as he half-suspected but was in denial about, he was involved in the deaths of several innocent people on New Caprica thanks to Cylon treachery. And He was nearly airlocked as a Cylon collaborator... And half the people who were about to kill him turned out to be Cylons. That can't be good for the sanity.
Buck Compton from Band of Brothers showed signs of a Heroic BSOD after he got shot in the Netherlands, then he finally freaked out after seeing two of his friends get hit with artillery fire near Foy.
On Star Trek: Deep Space Nine, Sisko breaks through Gul Dukat's wall of denial and makes him acknowledge that he really had been evil to the Bajorans when he was in charge of the planet. Dukat then suffers an epic Freak Out, and decides that from then on, he's going to be outright openly evil and damn well enjoy it. Which could be seen as a Nice Job Breaking It, Hero moment, considering what he would go on to do.
In Big Time Rush the band and Gustavo are ordered to make 3 christmas songs by their stuck up manager by the end of the day, forcing Gustavo and Kelly to delay their vaction to Fiji. But after already making 3 songs, the manger orders them to make one more song, Gustavo finally snaps and starts smashing instruments in the studio.
Take one Jack Bauer. Slowly restore his faith in the better side of humanity after all the years he's spent fighting for the greater good only to lose nearly everything important in his life. Then put him back in the game, see his potential love interest get shot dead, and then have a traitorous president sideline him to protect the murderers for her own benefit. End result? Let's just say things don't go well.
"Freak Out!" (1966) is the name of Frank Zappa's debut album. And it lives up to its name during "Help, I'm A Rock", "It Can't Happen Here", and "The Return Of The Son Of Monster Magnet".
"Freaking Out" (2001) is the name of one of Adema's most well known hits and it's a truly chilling metal song about the symptoms of a helpless person finally at the brink of their breaking point.
Pink has one in Pink Floyd's Rock OperaThe Wall, after his wife leaves him. He eventually reemerges from the worst of its effects but not before becoming a Neo-Nazi styled would-be dictator and terrorizing the countryside with his hammer army.
In "Doubt Academy", the usually very placid Roxy has a very violent one after discovering that Kuu murdered Tama and let Akari (her former girlfriend) be executed in his place. This also leads to her delivering a "Groin Attack".
Blanche has a permanent one in A Streetcar Named Desire after she is raped by Stanley and after Stanley tears off the paper lantern.
In Bastion, Zulf has one of these after he reads Venn's Journal. The second half of the game revolves around stopping what he does afterwards.
Manah, the Big Bad of Drakengard, has one of these after being finally defeated when the Anti-Hero refuses to kill her. It becomes clear that she wasn't only possessed but was genuinely insane. And in the sequel, she represses all those memories and joins your party. The moment she sees Caim, she screams for her mum and goes fetal. Can't blame her.
Sephiroth started out as a good soldier seemingly admirable guy, but once he figured out who he was, he went insane. Absolutely.Freakin'.Insane. In fact, since Crisis Core's release, we've learned that Sephiroth was the consummate SOLDIER. Powerful yet restrained, aloof yet compassionate, and considerate of others. Which just made his Face-Heel Turn all the more dramatic when Zack confronts him and they beat the shit out of each other. Even though it's really not the focus of the story.
Final Fantasy VIII includes a couple of these as Squall is forced to gradually open up. The first is after losing Ellone once more, when he realizes that even though he doesn't want to rely on anyone else that he could lose, he doesn't know how to keep going without someone else's help - he even asks himself whether anyone knows how to live for themselves before realizing that even that means he'd be asking for someone else to help him with his problems. Revelation after revelation breaks his normal, stoic demeanor and he slowly changes, culminating in his reaction to Rinoa's collapse after Edea's defeat, where he decides he absolutely will not let anyone else be taken away from him and ends up dragging Rinoa across a bridge that spans the length of a continent just to get to somebody who might be able to help and admits that he needs help from others to get what he wants. There's also another, minor one when Rinoa turns out to be a sorceress and is taken away by Esthar, where Squall nearly admits defeat before deciding he'll defend her to the very end with a little prodding from his friends, leading him to finally take command and open up to his team.
Princess Zelda turned into a creepy, screaming lunatic for one whole cutscene in The Legend of Zelda: Spirit Tracks, when Anjean revealed to her that a male demon was going to take over her body soon. She freaked out so badly that at one point the player has no control over the text boxes. She even scared Link while telling him that he needs to go out and bring back her body while she waits in the Tower like a good princess. It's played for laughs, still, the change was so frightening that not only was Link understandably scared to death, a good percentage of the players were as well. She snapped out of it rather quickly, when Anjean told her that she couldn't force Link to do it alone (like usual), since several traps in the Tower of Spirits needed teamwork to be survived.
Keisuke from Devil Survivor after finding out that the girl he was trying to protect Midori would be killed not by the demons she was slaying but by the people she was trying to protect.
Assassin's Creed III: Near the end, Daniel Cross has Desmond at gunpoint and is about to kill him when the cumulative Bleeding Effect of the Animus finally overwhelms him and he runs off, babbling insanely. Desmond finishing him off shortly thereafter is something of a Mercy Kill.
The Nostalgia Critic had an absolute meltdown when he reviewed the 3rd and last Teenage Mutant Ninja Turtles live-action film. Before he watches it, he tells the viewer to sit back and enjoy it. 5 minutes later, he has a Shower of Angst, twice, and starts to spew a lot of Angrish and screaming.
Salad Fingers. Almost every episode. Although he's already so batshit insane that his Freak Outs are basically just a higher level of craziness.
In Doom House, Reginald's inability to understand the anomalous nature of the Creepy Doll and his realization that the doll cannot be removed from the house or destroyed causes him to have a very epic one.
Reginald P. Linux: Why? Whyyyy?WHYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY?
In the webcomic Loserz, one of the protagonists (Jodie) has a temporary Freak Out after being isolated too long from her friends, starting with this strip.
The eponymous character of Dominic Deegan suffered one of these just before the breather arc where he and Luna take a cruise around the world. A list of grievances include losing his teaching job because no one signed up for his class the next semester, planning his upcoming wedding, one of his students becoming drastically ill, another teacher locking himself in his office, learning his longtime childhood comic book hero is getting aDarker and Edgier makeover and worst of all, The stores in his area stop carrying his favorite type of candy.
In fact, the impetus for going on said cruise is because if he didn't, he would have had a much, muchworseFreak Out.
Sal from It's Walky! is always full of Wangst, especially after when her parents were threatened, she told the villian she didn't care if they died, and he recorded her saying it, murdered her parents and taunted her with the recording. She a complete Freak Out after having glass caskets holding the decayed corpses of her parents dropped right in front of her.
The Meek. This happens to Luca when his wife is killed.
In El Goonish Shive, the hammers are magical weapons women (who know how) can summon out of thin air whenever men make inappropriate comments about women. They hurt, but they don't cause any permanent damage. Turns out they were specifically created to encourage such comments, since it made the men feel like they had received their punishment, and the women just enjoyed hammering the men. When die-hard feminist Susan found about this, she was not happy.
Jerry the Immortal: Don't worry, it's just a minor angst-induced Awakening! She totally won't be in a murderous rage afterwards!
(the dye from Susan's hair turns her clothes dark blue, her hair turns from blonde to dark blue, and her eyes glow black as she floats a few feet off the ground)
Jerry the Immortal: Okay, so maybe it's a major angst-induced Awakening.
Gamzee has one of these shortly after Dave shows him ICP.
Rose has two within a very short time-frame: first after she found out Jack killed her mother, and the second when she asked an omniscient fortune-telling device whether or not the Gods of the Furthest Ring were evil. The answer appears to have turned her into a Humanoid Abomination.
although she seems to be (mostly) back to normal after dying, reviving as her dream self, then ascending to God Tier.
You can tell when a First Guardian goes through one of these: their text becomes huge and crackles with energy. Examples: Doc Scratch and Jadesprite.
Act 6 is all about main characters freaking out. John winds up snapping after Davesprite skips out on his birthday, having been previously worn down by the boredom and isolation of being on the ship; Terezi allows Aranea to restore her sight because her confidence has been broken by meeting her dancestor and caliginously dating Gamzee; the Beta Kids experience a collective Freak Out (except for Dirk, who's largely immune to its mental effects) when they go Trickster; and Beta Jack Noir experiences one when he receives Lil Cal while in prison and falls victim to its curse.
Teen Titans: Happens to Raven in her numerous appearances, most notably after her Mind Rape at the hands of Slade. The episode "Haunted" is devoted to one massive Freak Out after another that Robin endures when Slade supposedly returns from the dead.
Danny Phantom: Vlad after his beloved clone of Danny is destroyed. He almost was this close to killing off two half ghosts if not for a timely intervene by Danny's friends. But he spent the rest of the series tormenting Danny. One could say that Vlad's Freak Out in that episode intentionally led into his different motives in the next season...or it could just be Motive Decay as a result of different writers handling the show. The Freak Out did lead to Vlad having different motives at the start of season 3 (tormenting Danny), which was written by Marmel. After that, though, the newer writers led to Motive Decay and made Vlad a run-of-the-mill villain who wanted to take over the world.
Aang goes into an Unstoppable Rage multiple times in the show whenever he suspects his friends to be in danger, when Appa goes missing, or when he finds Monk Gyatso, who was like a father to him, dead. Azula has a permanent one and goes insane. But she was shipped off to a mental health facility and, according to Word of God, will possibly make a recovery in the future.
Aang could be viewed as having undergone a Freak Out upon learning of the genocide of his race that lasted most of the first season, and then on and off until he finds peace in the Grand Finale. In the flashbacks with Gyatso and Bumi he's earnest but calm and somewhat reticent, and his hyperactivity might just be a way of trying to distract himself from the horror.
Kenai does this in Brother Bear when he realizes he turned into a bear.
Being a failed science experiment with more mental issues than even the most skilled therapist could count, Adventure Time's Lemongrab is CONSTANTLY in the midst of a freak-out.
Fry from Futurama suffers a Freak Out after being erroneously sent to an insane asylum for robots. Obviously, the staff (all robots) don't notice this simple detail, and continue to treat him as such. He would be released weeks later when he, as described by the doctor, "no longer suffers delusions of humanity."
He also freaks out in "Roswell that Ends Well", when he realizes he is his own grandfather.
Ned: Calm down, Neddly diddily diddily diddily, doodily. They did their best shodaiddily iddily iddily diddily diddily. Gotta be nice, hostidididildilidilly ah HELL diddily ding dong crap! Can't you morons do anything RIGHT!?
Subverted in the episode "D'oh-in in the Wind." Homer, alongside his mother's hippie cohorts, attempted to "freak out squares" in Springfield. The joke was on them, however, as Ned Flanders took Homer's suggestion of "expand your mind" as a tip, apparently not knowing what Homer might have actually been referring to (ie, expanding the mind with drugs), Homer's cosmic fool stint was decried by Krusty the Clown as being "weirdos," and Skinner's reaction to Homer's closing the "conformist-factory" (ie, the elementary school) was simply dejection with the kids' reactions being a lot of cheers. In fact, the closest to an actual freakout that occurred was his son, Bart, and that's only because he was embarrassed that his dad arrived to pull off his hippie stunt at school.
In The Batman, Officer Bennet suffers a Freak Out when he gets captured and mentally tortured by the Joker, followed by getting exposed to chemicals that turn his body into morphable clay. After spending two seasons as the good friend of main character Bruce Wayne, Bennet becomes the villain Clayface after the two-part season finale that focuses around this event.
Daffy Duck's Freak Out in Duck Amuck is the stuff of legends.
Happens to Twilight Sparkle in the My Little Pony: Friendship Is Magic episode "Lesson Zero". When she realizes she doesn't have a weekly friendship lesson to present to Princess Celestia, she grows increasingly crazy trying to find one, culminating in a fully-loaded Freak Out the likes of which have never been seen on the show before (which is saying something, given the show's other examples).
In "Party of One", Pinkie Pie gets it into her head that her friends don't like her parties any more, so she starts throwing parties with her new friends - a bag of flour, a bucket of turnips, a pile of rocks, and a collection of lint - all of which she's named and given voices. Then she starts imagining they really are talking to her...
These freak outs have been classified by fanon as "Cutie-Mark Failure Insanity Syndrome" a condition that causes ponies to lose control and over-react to situations that cause them to doubt the purpose in life they found when they received their cutie-mark.
Lois of Family Guy when they ran out of paper towels on Christmas.
Donald Duck's hunger-induced nervous breakdown in Mickey and the Beanstalk.
Stu of Rugrats has one when Angelica starts to wear on him after she pretends to have broken her leg.
T.J. from Recess, after being placed in "the box" (A square drawn on the blacktop which students have to stand in for punishment). He mocks it at first, but soon, it begins to break him, eventually causing this.
In Beavis and Butt-Head Do America, Beavis has one when the plane he and Butthead are on takes off, causing him to scream "WE'RE GONNA DIE!" over and over. Later on, when the duo fail to find Dallas, he has another one with his "We're Never Gonna Score" speech.
Donna has this in the final episode of The Cleveland Show when she finds out that her ex-husband is sleeping with her mother.
If you've ever had a moment when you feel like you'll explode if you don't scream and let out your problems, odds are you're on the verge of one.