Tragic Mistake

Tragic Mistake is the event where a hero is given a clear choice, but because they choose poorly, it results the disastrous event that brought the huge impact on their life that made them more miserable than ever. The said mistake may caused by the said hero's own flaws, but sometimes fate also pressed them to chooses poorly as well. While the hero and/or their allies may not realizing the consequence of their wrong choice, that moment is crucial to the beginning of unfortunate event that ranges from merely the hero's tragic downfall to the chain of disastrous events.

The results of this bad choice lead inexorably towards the hero's catastrophic end - had the hero chosen correctly at this point, the catastrophe could have been averted. The said mistake also the crucial part of their story.

Star Wars

 * Anakin Skywalker had made many mistakes prior to this point, but what pushed him irrevocably over to the Dark Side was his decision to save Emperor Palpatine instead of letting Windu execute him, leading directly to Mace Windu's death and leaving him no chance to go back as well as the downfall of the Jedi Order, including Order 66.
 * Another point of no return for Anakin was when he impulsively (and unnecessarily) refuses to see Padmé Amidala, trying to talk him down and Obi-Wan Kenobi stowing away on her ship, as anything but an attack on him. This results in him Force choking his wife and dueling with his former Jedi Master, ending with him having his three remaining limbs chopped off and getting burned very badly by lava. The old Anakin might have been able to find a way to save his wife from dying in her childbirth, but after waking up in the black suit, he realizes that his own fears ends up killing her.
 * Though Anakin is not necessarily blamed (again) even after his redemption and demise, the impact of both his and evil actions as Vader proved to be greater than either he or his son Luke expected: Ben, Luke's nephew and apprentice as well as Han Solo and Leia's son, whom upon learning Anakin's dark past as Darth Vader, decided to embrace the dark side and become Kylo Ren, causing a major setback on Luke's dream to restore Jedi Order to the point that he went to exile until Rey discovered him and give him hope.

Harry Potter

 * Harry Potter refuses to be taught Occlumency by Severus Snape because of their hatred and mistrust for each other where much to Harry's shock, their said hatred and mistrust for each other were caused by Snape's own bad history with James Potter long before James himself changed into better man due to his love with Lily. This allows Voldemort to send him a false vision of Sirius held captive so that Harry could run to his rescue. This results in the all-out fight that ends with Sirius' death since in his impulsiveness Harry also neglected a device which would have allowed him to communicate to Sirius immediately and verify that he's fine.
 * Prof. Snape himself also has of his own, where he ruined his friendship (and any chance for romance he might have had) with Lily when he chose the Dark Arts and became a zealous Death Eater. He then relayed a prophecy to Voldemort which causes him to target Lily's son, resulting in the murder of her and James. While he eventually decided to be the ally for Harry from there on, his own personal hatred with James winds up worsen his relationship with Harry until he eventually revealed his true agenda when Voldemort killed him for mistaking him as the master of Elder Wand that led Harry to forgive him. In certain point of view, had Snape put aside his difference with Harry (which in turn convinced Harry to do the same) from the moment where they met in Harry's first year in Hogwarts, he won't have to fail in taught Harry Occulumency that winds up resulting Sirius' death nor have hostilities that they had now at least until Snape seemingly murdered Dumbledore which actually done as mercy killing.
 * Among unfortunate mistakes that Albus Dumbledore ever done, the most tragic one was tempted to start a plot against Muggles with Grindelwald, and in his lust for power caused his sister's death when his brother confronted Grindelwald.
 * Horace Slughorn's was allowed the young Voldemort Tom Riddle to flatter him too much and revealed to him information about making seven Horcruxes for maximum power, which resulting deaths that the future Dark Lord required to create his said Horcruxes, Hagrid being reduced to the gamekeeper as the partially succeed framing attempt as means to cover his tracks and Lily's own death. Fortunately, he had the chance to redeem this through her son Harry whom working on helping Dumbledore' investigations.
 * Sirius Black was when he let Wormtail be the secret keeper to protect Potters, only for Wormtail betrayed them and brutally massacred innocent muggles and framed the crimes to him, resulting him sent to Azkaban until he uses his Animagus powers to escape. Another mistake would be mistreating his house-elf Kreacher, resulting the house-elf betrayed him and leaving him to die at hands of Bellatrix.
 * Albus Severus Potter and Scorpius Malfoy's attempt to alter the past to improved their current reality with a Time-Turner proved to be as the second attempt to alter the past resulting the bad future that only happened should Voldemort successfully killed Harry Potter. Though they managed to restore the reality back to when it previously was prior to their travel back in time, such attempt to undo what they did is not enough as Delphni, who revealed to be Voldemort's daughter that believed that Voldemort's defeat supposedly not happened, tries to save Dark Lord and it took their efforts and aid of their parents as well as Ron's family to stop her.
 * Percy Weasley's disowning his family of loyalty to the corrupted of Ministry of Magic, he even refuses to believe Harry Potter that Lord Voldemort has returned and Cedric Diggory murdered and Cornelius Fudge discredits him and Albus Dumbledore and informs that Cedric's death is a tragic accident. However after Cornelius Fudge is been overthrown by the wizarding community for lying of Voldemort's return, allowing Dolores Umbridge to became Headmistress of Hogwarts and Cedric's fate, he then realizes that Harry was right about Voldemort. He finally realizes his errors of his ways of his family after his brother Fred Weasley was killed in the Battle of Hogwarts and apologizes to his family for disowning them and avenges his brother.

Other

 * When Peter Parker arrogantly refused to stop for five seconds to stop a crook stealing the wrestling manager's money rushing past him, telling the cop chasing the guy it wasn't his job (along with the fact that the manager had cheated him out of the prize money just before the robber showed up), his life was changed forever; the same crook would later murder his uncle, Ben Parker. While that mistake defined what he is, the lesson was learned in the harshest way possible.

Live-Action Films and Television

 * The Asset: Unaware of his new environment, he makes the mistake of eating one of Elisa's cats and clawing Giles.
 * Carlito Brigante: Carlito's case mostly involving poor judge on a character that he supposedly either spare or not: Carlito had the troublemaking Benny Blanco at his mercy but let him live because he was a reformed man. Carlito also knew never to trust Pachanga and said he'd take care of him but he never found the time.
 * Claire Dearing: Claire's mistake that led her indirectly contribute destruction and deaths in Jurassic World at the hands of Indominus rex was her ignorance with the fact that dinosaurs actually have emotion and feelings instead of simply beasts with no intelligence as well and gives Owen a cold shoulder on her poor management on Indominus. That's until she realized that whatever treatment that she arranged for Indominus wind up destroyed what has left of her innocence where the hybrid killed many people by manipulating pterosaurs and raptors where Zach and Gray Mitchell nearly became the hybrid's victims as well as threatened the fate of the park.
 * Rose DeWitt Bukater: As the RMS Titanic is sinking, Rose is ordered to get on board a lifeboat, since only women and children were being boarded at that point. As the lifeboat is being lowered down. Rose, not wanting to leave Jack Dawson behind jumps off the lifeboat onto one of the lower deck floors. Jack and Rose then reunite at the grand staircase. They then get chased by an enraged Cal Hockley, who gives up pursuit at a flooded dining room. Unfortunately by the time Jack and Rose get back to the boat deck, all the lifeboats have been deployed and as a result, partly because the RMS Carpathia hadn't yet reached the Titanic, Jack and Rose are forced to retreat to the back of the ship in order to stay out of the freezing water for as long as possible just as the boat deck starts to flood and the Titanic starts to tilt. Fortunately Rose survives the disaster but Jack dies of hypothermia in the North Atlantic ocean.
 * Roger and Anita Radcliffe: When Roger and Anita go out for a walk to the park whilst taking Pongo and Perdita with them, they didn't take enough precaution in ensuring Pongo and Perdita's pups' safety from dalmatian kidnappers: Two bandits named Jasper and Horace Badun who are watching them from the shadows has study the whole situation in their house as they easily break in, lock Nanny in the cupboard, and stole the puppies without leaving traces. When they returned home, Roger and Anita feels saddened with what has happened and their mistakes that gave the thieves advantages. Fortunately, a group of farm animals whom knew where the thieves hiding at able to save the day by incapacitate the thieves includes their leader Cruella de Vill one by one not only to save Pongo and Perdita's puppies, but also other kidnapped homeless dalmatian puppies.
 * Rex (Babe): Rex was insulted at Babe's action of herding the sheep, he attacks Fly furiously injuring her leg. Arthur Hoggett sees this rushes to break them up, in his rage Rex accidentally bit his right hand in the process, causing Esme Hoggett to glare at him for it. When Babe tries to talk to him, he chases him away in anger, but he was held back by his leash with Arthur Hoggett witnessing him, calls the vet. The Vet then sedates him, losing his ability of herding the sheeps in the process. When Babe runs away thanks to Dutchess the Hoggett's nasty cat revealing to Babe that farmers eat pigs, Rex now realizes how Fly is heartbroken is without Babe and how much good he has done, regrets his behavior earlier, rushes to find Babe and probably scolds Dutchess furiously for saying those terrible words to Babe.
 * Chance: Chance has a fear of going to the "bad place". When Chance, Shadow and Sassy are been put into their cage at the San Francisco International Airport by their owners so that they all could get board on the plane, Chance panics thinking that he and the others will be take to the dog pound despite Shadow's pleads that they will not take to the dog pound due to his actions that made his owner Jamie Seaver mad, he breaks free from his cage and foolishly returns to the airport lobby ultimately leading him and the others to be left behind as a result of mistaken the San Francisco International Airport for a dog pound.
 * Optimus Prime: Optimus Prime's tragic mistake because he was reprogrammed and brainwashed by Quintessa to retrieve the Staff of Merlin and has doomed Earth as Nemesis Prime.
 * Marty McFly: Marty buys a Sport Almanac book while in the future. Unknown to him that old Biff Tannen was watching him and steals the Delorean Time Machine, while he was helping his girlfriend Jennifer and Biff goes to the past and brings the Sport Almanac to his younger self, resulting in an alternate timelime, where his father George Mcfly being murdered by Biff in 1973 and Emmett Brown declared insane and is committed. He was able to reverse Biff's change of the timeline with help from Emmett, thus returning everything back to truly was.
 * Bob Seaver: After his marriage with Laura Seaver, he takes their children's pets Shadow, Chance, and Sassy to their friend Kate. But a few days later they are no longer in Kate's farm anymore. Peter Seaver his elder son harshly scolds him for leaving them at the farm rather than to take with them.
 * Sonny Quinn: First, he unleashed Slappy the Dummy from Haunted Halloween, allowing him to sabotage his Tesla Tower model. Later, he answers a phone call from his mother Kathy while he and his best friend Sam Carter are being attacked by evil gummy bears, thus allowing Slappy's Halloween monsters to capture her so their master can turn her into a human puppet.
 * George Newton: First, he hates his dog Beethoven, he gets an arguement with Alice over Beethoven's antics that ruined his barbeque for Brad and Brie and Emily fallen on the former babysitter's pool and Alice tells him that Beethoven is the one who could give their children the ride they deserved. He sees attacking Dr. Herman Varnick, not realizing that it was Varnick who really hit Beethoven and ordered him to bring him to his clinic. George then brings Beethoven to him leaving his children, Ryce, Ted and Emily heartbroken, with Emily calling him a dog killer. George Newton then soons discover Varnick arm has no bite marks meaning the attack was fake, when he tried to prevent him from getting Emily, realizing he was being tricked and lied by Varnick and punches him for it.
 * Alvin: ditches the sing-off for a football game, thus forcing his brothers to forfeit the sing-off and giving the Chipettes a victory that they're not proud of. When he finally appears, the auditorium's empty and Brittany calls him out on his selfishness before leaving. When Alvin returns home, his brothers pretend to be asleep and ignore him.

Disney/Pixar

 * Marlin: Out of his own fear over Nemo's safety and trauma over his loss by an aggressive barracuda that massacred his eggs and killed his wife Coral, when he tries to advices Nemo to avoid the diver's boat, his overprotectiveness and fear get his best on him and resulting his son provoked to rebels and taken away by divers. Nemo managed to prevent him from repeating the same mistake when rescue Dory and unfortunate fishes whom snared by fishermen's net.
 * Mr. Potato Head: Despite that Andy Davis already missed Woody, he mistakes Woody for murdering RC who was actually trying to rescue Buzz Lightyear who was been attacked by Scud Sid Philip's dog and he orders the others to toss him overboard. While celebrating Bo Peep then see Woody riding in RC with Buzz, realizes that Woody was telling the truth. He then realizes what he has done and help them board their vehicle, though as retribution of his bad actions, he had to put himself back together due to RC accidentally crashed on him in Buzz and Woody's attempt to put him back into truck possibly as payback and punishment for the mutiny against Woody earlier and not realizing that Andy already missed Woody. He is then scolded by Buzz Lightyear for it after he requested for a rest during the rescue mission on Woody, after he was kidnapped by Al McWhiggen and he is still regretting it.
 * EVE: After purposely freeing the bots, and making the Stewarts send a warning, EVE then realizes her mistake of sending WALL-E away.
 * Carl Fredriksen: After a construction worker damages his mailbox by accident, Carl assaults the worker by hitting him on the head with his cane. Carl is then branded a "public menace" & taken to court to face trial for his actions. The court force Carl to move to a retirement home. This endangers Carl's choice to stay in his own house, where he has been living, since his wife Ellie died.
 * Anger: In a desperate attempt to make Riley happy again, Anger comes up with an idea of running away from San Francisco and return to Minnesota. However, the idea of running away proved to be a terrible mistake as the emotion console began shutting down and Riley was turned into an apathetic person without any feeling at all. When Joy and Sadness returned, Sadness was able to fix the console by removing the idea so Riley can change her mind.
 * Princess Atta: She learn the truth that the warrior bugs that Flik brought was P.T. Flea's troupe, she banished him and the troupe, causing her sister Dot to become heartbroken and depressed of her actions. However Flik's words are proven correct when Hopper and his gang take control of the island, she puts her entire colony in danger and her mother The Queen's downfall and without Flik and the troupe, they can't get rid of Hopper and his gang forever.
 * Megara: Motions of events that led to Megara's heroic sacrifice that caused his current lover Hercules mourns over her dead body can be traced back from when she made a deal with Hades to save her first boyfriend's life (which in TV Series revealed as Adonis). Unfortunately, he later left her for some other woman, abandoning her and leaving her heartbroken and a prisoner of Hades. This traumatized her so much that she became bitter, though when finally met Hercules whom became her true love, she finally given chance to redeemed herself by sacrificing herself to save Hercules where the process not only to allowed the demigod to reclaimed his powers and freed her from her pact with Hades, but also resulting her demise. Fortunately, she later get better after revived by the demigod whom reclaimed her soul.
 * Mr. Incredible: Because he arrogantly detested Buddy Pine's attempt to aid him and recklessly saved a suicidal man whom doesn't wanted to be saved as well as disasters that he unintentionally caused, he not only forced all Supers to retire and into hiding (which somehow also decrease the crime rate), but also turned Buddy into the ruthless supervillain Syndrome whom sought to make the term "superheroes" redundant to the world which includes murdering huge number of Supers populate.
 * King Triton: Because of his hatred for humans and learns that his daughter Ariel has fall in love to a human whom she saved from drowning that he loses his temper and begins destroying her collections and completely ignoring her pleads to stop, but he then realizes what he has done and leaves her in shame, this also lead Ariel to search of Ursula the Sea Witch.
 * Simba: Simba's that resulted Scar to usurp the rule over Pride lands as to listen Scar in the first place.
 * After falling on Zira's ambush to kill him, he defies his father's paw prints that he himself must follow by exiling Kovu believing he was involved the ambush, forbids his daughter Kiara to near him, causing her to angrily tell him that he will never be Mufasa and that will happened if he still refuse to reconsider his mistakes.
 * Sulley: Sulley's was letting out his signature roar to scare a robot child for simulation, which horrified Boo so much that she became too scared of him, which interfered their relationship.
 * Wreck-It Ralph: Ralph's was trying to earn himself a medal so that he would win the respect and hearts of other video game characters, especially the Nicelanders. But by doing so, he game jumped to Hero's Duty caused a lot of damage in his absence, his game was "Out of Order" and think that Mr. Litwack was planning on unplugging it if Ralph didn't come back. He also accidentally took one of the game's Cy-Bugs into Sugar Rush, whose candy allowed the bug to multiply itself into an enormous frenzy swarm of giant bugs with the potential to decimate the arcade.
 * Tarzan: Tarzan's of bringing the humans to the gorillas, caused him to fight the gorilla leader Kerchak just to protect his new friends, only to betray their family and disobey Kerchak's orders to protect their family, which leads him to renouncing his membership to the gorilla family, sadly discovering his true heritage that he is a human, saying goodbye to his adoptive mother Kala, as well as leading to the hunter Mr. Clayton to betray him, Jane and her father by setting the evil hunter's plan to capture the gorillas into motion.
 * Fa Zhou: He accepts the conscription notice from Chi-Fu who tells him to teach his daughter Mulan's tongue in a man's presence, after he silenced her and ignoring his injuries. While training his injuries prevented him. During dinner, he argues with Mulan that she need to learn her place like what he did, causing her run off in tears, but he ignores her and continues eating, his wife Fa Li and mother Grandmother Fa are saddened at his actions. Before going to bed, he comforts his wife, but she run off in tears, knowing he will not survive the war and realizing that Mulan takes his place and will be killed. After Shan Yu was finally killed and Chi-Fu resigning from his post to avoid facing trial for his crimes against Mulan after her identity is been exposed by Shan Yu by  ordering LI Shang to execute her, Fa Zhou was finally reunited with Mulan who presents him the Sword of Shan Yu and the Emperor's crest and he hugs her claiming that she is the greatest gift and honor.
 * Nakoma: Nakoma's of sending Kocoum after Pocahontas, resulted in the warrior getting killed by the settler Thomas, John Smith accused of Kocoum's murder, Pocahontas getting harshly blamed for her foolishness causing his death, and even leading to war between the Native Americans and the English Settlers.
 * Basil of Baker Street: He admitted that he let his ego get in the way after being humiliated by Ratigan and his gang, which showed he had a caring side, unlike Ratigan. Later on as he and Dawson lie on the trap, he sulked over his mistake of falling for Ratigan's trap.
 * Dr. David Q. Dawson: Basil apologized to him for yelling at him for not watching Olivia before she was kidnapped in the toy store by Fidget, taking her to Ratigan's lair.
 * Rabbit: He refused to make Easter, after Tigger stealed his role as Easter Bunny. When Spring cleaning has come and he wonders, where Pooh and the others are, thinking they're late and the narrator tells him that they're gone and move away. When he finally realizes after finding Roo's drawing of himself and Rabbit together, he now realizes that his friends (including Christopher Robin, Owl and Gopher) have moved away because of his selfishness and the next day, he realizes it's only a dream and still has a chance and prepares for the Easter and giving all of their easter things to them.
 * Darkwing Duck: Blinded by his own pride, arrogance and ego, Darkwing Duck stubbornly and rudely refused any assistance from the Justice Ducks (Steggmutt, Neptunia, Gizmoduck and Morgana) to fight against the Fearsome Five and insisted to take on the villains alone which however does not end well for him, he then realizes his mistake as his mistake as he learns that the Justice Ducks have been captured by the Fearsome Five.
 * Kuzco: Pacha tries to warn Kuzco about Yzma and Kronk trying to kill him, only for Kuzco to blow him off, believing they were there to bring him back to the palace. He then orders Pacha to go away, believing  he's  the one trying to keep him from getting home. Only when Kuzco overhears Yzma and Kronk talking about killing him does he realize he sent his only friend away for nothing.
 * Miguel Rivera: Due to his hero worship for Ernesto De La Cruz, Miguel foolishly believed that he was his great-great grandfather and hoped that he will receive his blessing in order to return back to the Land of the Living. However, his real great-great grandfather, Héctor, revealed to Miguel that Ernesto is a liar, a murderer and a thief because he poisoned Héctor with a toxic drink due to the fact that he wanted to return to his family. He also reveals that Ernesto stole all of Héctor's songs including the famous song that was meant for his daughter, Coco, Remember Me. And because of that, Miguel realized that everything he knew about so-called idol was a lie.
 * Kenai: Killed Koda's mother out of anger and vengeance. As a result the great spirits punished him by transforming him into a bear, he was later hunted relentlessly throughout the film by his brother Denahi who thought he was the same bear Kenai killed earlier.
 * P.T. Flea: Due to the Flaming act went into a disaster, he fires his troupes, allowing Flik to hire them believing as Warrior bugs due to the confrontation at Bug Bar with the Fly Brothers. Later after learning the Flaming Act was a success, he goes to the Ant Island and blows Flik's cover, making Princess Atta to realizes that Flik lied to her which he wasn't and banishes him along with the Circus Bugs. However this was a fatal mistake as a result of her actions and without Flik and the Circus Bugs, she puts her entire colony in grave danger and brings the downfall of her mother the Queen, when Hopper takes over the island due to the lack of offering for them. When Flik, Dot and The Blueberries used the Fake Bird to scare Hopper and his gang, P.T. Flea mistakes it for real and sets it on fire and ends up aiding Hopper and his gang. Upon witnessing Flik being beaten by Thumper and Hopper insulting the ant colony and the circus bugs, he realizes his mistake and teams up with them to deal Hopper and his gang with the later getting killed and eaten by the bird.

DreamWorks

 * Shifu: Shifu's prior to events in Kung Fu Panda was during trained Tai Lung, he was so proud of his talent that he forgot to taught his said student humility, which contributes to the leopard's fall from grace when it's revealed that he was not meant to be Dragon Warrior. Master Oogway also pointed out that due to the said mistake, Tai Lung's arrogance turned into the very darkness that consume his heart and made him evil.
 * Hiccup Horrendous Haddock III: In How to Train Your Dragon 2, Hiccup's most tragic mistake was not listening to his father or anybody else about Drago Bludvist. Because of his overconfidence in his ability of being a diplomat and bringing peace to dragons & humans, Hiccup believes he can reason with Drago to not wage war and refuses to listen to Stoick & Valka about Drago's psychopathy and the fact he could not be reasoned with. When Hiccup tries to reason with Drago, this leads to Toothless being hypnotized by Drago's Bewilderbeast and indirectly kill Stoick. At his father's death, Hiccup's confidence is shattered and is struck with grief; for not listening about Drago and leading his father to be killed.
 * Verne: His distrust towards RJ became so strong, he tried returning all the food the others stole, which later got destroyed. He argues with everyone until he calls them stupid and naïve in a blind moment of jealousy, hurting Hammy's feelings in the process. Verne realises too late that he went too far and he costed his friendship with the others.
 * Alex the Lion: Alex's ignorance with life outside the zoo and lack of control over his feral side (which he recently discovered) counted as this, as it led him blinded by feral instinct to devour his own friend Marty (where he would've succeed had Julien not interfered).
 * The second that Alex done was when he listened to Makunga whom uses his lack of knowledge about cultures of his kind against him and his family (by tricking Alex tinto challenging Teetsi would be dance contest, but in reality it was mortal kombat) as means to take over the pride.
 * However, Alex's very first was not entirely his fault, as Marty also shares the blame: Marty's own was in form of wish to go to the wild was without concerning his friends' well being, particulary Alex as well as not realizing that the wild is the place where carnivores won't hestitate to devour weaker animals.

Others

 * Terra: In Teen Titans 2003 TV Series, in a desperate attempt to control her earth powers, Terra chooses to join Slade whom promised her to trained her after failed to have Beast Boy keep this from other Titans, which turned out costs her friendship and love with Beast Boy.
 * Cameron Corduroy Wilkins: Cameron made a poor choice of refusing to trust Alejandro instead of accepting it when he was in a dangerous situation. After Cameron is eliminated from the competition due to injury, Gwen and Zoey say their goodbyes, Mike comes up to him and reveals himself to be Mal and he was the one who left him to fall. He should've listened to Alejandro earlier and would've known what was going on.
 * Wyatt: Wyatt's was his show-off habit not improved the trouble that he and his friends face, but rather worsen it instead.
 * Red & Yellow: Ivory, arriving on the Island by the winds, explains to Red, Yellow and Mango that in their absence, Grey Green & The Silvers easily dominated their friends back in New York. Without Red and Yellow to help, the remaining Larva Rangers were defeated by the predators; Ivory's frail body is what made him fly by the winds. Mango couldn't believe what happened while the other Larva were horrified that their friends were in danger and they could've saved them
 * SpongeBob SquarePants: In "The Legend of Boo-Kini Bottom", SpongeBob realizes the horror of Patrick's so-called philosophy, "Scary equals funny" as it endangered the lives of his friends after the Flying Dutchman captures their souls and are holds them hostage.
 * Steven Universe: Steven's which endangered his friendship with Garnet is refuses giving the mirror to her and in blind anger, hits Garnet in the heat of their argument. He also realized about his visit in Homeworld was a bad idea.
 * Batman (The Lego Movie Series): He realizes in The Phantom Zone how big the mistake he made when he drove Dick, Barbara and Alfred.
 * Lapis Lazuli: Her decision to fuse and imprison Jasper in order to defeat her for good and save Steven's life becomes this in months until Alexandrite rescues her.
 * Homer Simpson:
 * Bart Simpson: He has a nightmare and feels very guilty for burning Lisa's centerpiece, something which made him realized that it was a mistake and he must undo before it gets worse.
 * The Powerpuff Girls sad that they got so tempted by their new toys, they think the Professor is dead because of them, but in truth, he's alive, because there were only toy guns.
 * Cera: Cera's ego led to the death of the other dinosaurs and her friends being endangered from taking the wrong path. She however was too headstrong to admit her mistakes.
 * Topps: When the Thundering falls stop running due to the flying rocks blocking the water passage in the Mysterious Beyond, he begins to lose his mind and gets an arguement with the other Great Valley inhabitors and need to take turns. When his daughter Cera is been bullied by Hyp and his gang by pushing Nod right into them with Cera getting out of the way and Littlefoot getting hurt by them, he thinks Littlefoot did waste the water calling him a bad influence which angers his grandfather saying to him that his grandson is not a bad influence and leading his long lost son-in-law Bron Littlefoot's father to dislike and hate him, when he learned this. When he gets an arguement with Cera claiming the he only want what's best for her, heartbroken, she runs off and again further to lose his mind. He even refuse to let a spike tail drinking from the river and has lose completely his mind. After witnessing Hyp been scolded by his father for putting himself in danger, bullying his daughter and Littlefoot and his friends and leading Littlefoot getting insulted, he tells him not yell at him and shows what is right at what he care. After the Thundering falls finally returns when the block passage is clear, he apologizes for his behavior and earning Bron's trust when he finally meets him.
 * Beth Smith: She mistakenly shot Mr. Poopybutthole she thought he was an alien parasite.
 * Goldie: She mistakenly Edmond as the bad kitten that Pinky told her about and she shoos him away leading him to get captured along with Patou and the others by Pinky. She then realizes what she has done at seeing this and informs this to Chanticleer.
 * Dracula (Hotel Transylvania): Drac realizes that he got in the way after his daughter Mavis zinged with Johnny.
 * Twilight Sparkle: When she is at the mercy of Tempest Shadow, Twilight makes the mistake of failing friendship.
 * Emmet Brickowski: After destroying the ceremony, Emmet makes a big mistake of starting Armamageddon.
 * K.O.: In his haste to help Mr. Gar on a stakeout, K.O. ends up breaking open a sealed door to a secret cave filled with Glorbs, which is what Shadowy Figure had planned.
 * Jaune Arc:  After Ruby shouts out him for manhandling Oscar, Jaune is visibly horrified as he realizes that Oscar is afraid of him and that he roughed up an innocent boy. His guilt only worsens when he finds out that Oscar left the group.
 * Mr. and Mrs. Turner: They mistakenly punish Timmy after Vicky tricked them into thinking that Timmy had vandalized their house, but after receiving pure evidence from "Deep Toot" (Tootie in disguise), they have finally discovered that Timmy was right about Vicky and that he was framed by her.
 * Leonardo (2003): After surviving the final battle with the Utrom Shredder with his brothers and master, Leo develops Post Dramatic Stress Disorder. Over the past few months he become more serious, petulant, brooding, ill-tempered, aggressive, violent, hostile, easily provoked and surly toward his friends and family. His anger has reached t's toll of accidently injuring Splinter in an uncontrollable rage during a training session before making a pilgrimage across the world to meet the Ancient One, Hamato Yoshi's sensei. After realizing that there was nothing more he couldn't done and did the best he could, he finally understand that he's been his own worst enemy.
 * Helga G. Pataki: When she realizes how selfish was being to be a bully and hostile with Arnold which she supposed to care of him after getting captured by Lasombra.
 * Lucy/Wyldstyle: When the Systar System invaded Bricksburg, Lucy believed that they were threatening to destroy everything and bring an apocalypse to their LEGO universe. As a result, she darkened most of her hair with black marker so she can get people to think she was cool and grown-up. She even wanted to get Emmet to change his personality and darken his tone to make him tough like her. However, as the film progresses, she realizes that the Systar System never meant to antagonize Apocalypseburg. For they merely failed to communicate their desire to coexist in peace since she and her friends attacked them instead of making friends with them. She even realized her tragic mistake in attempting to change Emmet to make him as tough and grown-up as she is when he was tricked into bringing Armamageddon into the LEGO universe by Rex Dangervest. At the end of the film, Lucy learned a great lesson: you can't pretend to be something you're not and you can't force people to change.

Anime and Manga

 * Tai Kamiya: When he was young, Tai Kamiya's younger sister, Kari, almost died due to his own negligence. Tai arrived home to find his sister (who was 4 or 5 at the time), staying home from kindergarten due to an illness. He took her outside to the playground to practice kicking the soccer ball, when she suddenly collapsed onto the ground. She was rushed to the hospital as her illness worsened, and Tai's mother, scolded, slapped and shouted at him much to her husband and their father's shock for recklessly endangering his little sister's life. Kari remained in the hospital for weeks with possibly pneumonia, and almost didn't make it. When their parents finally brought her home from the hospital, Kari apologizes to her brother for not being to kick the ball very good, tells him that he'll never want to play with him again, causing Tai to break down in tears of guilt.
 * Ash Ketchum: In Pokémon Scent-sation! - He believes that perfume is a waste of money, which gets him kicked out of the shop for being very rude. Worse, the same people working in the shop work in the Celadon Gym and also forbid him from challenging Erika, the Gym Leader. Then he asked for Team Rocket's help to get in; but after James, Jessie and Meowth escape with the perfume formula, they blew up the Gym by detonating a bomb. Ash realizes he made a terrible mistake and feels very guilty, he should've apologized instead of sneaking in.
 * Alain: When Alain began his journey as a trainer and met up with the Team Flare leader, Lysandre, he was told that his team is using Mega Evolution energy to protect the Kalos region to be the strongest and help Chespie's recovery. He was later told to capture the Zygarde core whom they've called Z-2. However, when Team Flare attacked Lumiose City and abducted Ash after the Kalos League, Alain came to realize that everything Lysandre and his team ever told him were lies as they manipulated him to gather the Mega Evolution energy to recreate to world with Zygarde under their control. Alain felt betrayed by them and began to feel a great sense of guilt in him as he collapsed in frustration and anger. It wasn't entirely his fault, he was only doing this for Mairin and Chespie's sake as he never meant to hurt anyone.
 * Sayaka Miki: Though it could be said that Sayaka Miki's deal with Kyubey in the first place is the mistake that leads to her downfall, her actual act of Hamartia is when she refuses to cleanse her Soul Gem, because she's full of despair from seeing Kyousuke Kamijou (her childhood friend) accepting Hitomi Shizuki's love confession. Her despair not only turns her into a witch, but also leads to her and Kyouko Sakura's death.
 * Harogumo Ootsutsuki: He realized that he has done this by having Asura as his one and only successor, unknowingly allowed Black Zetsu worsened the rivalry between Asura and Indra that would lasts for generations everytime they reincarnated into their descendants. This ultimately undone with the brothers' latest incarnation, Naruto and Sasuke, eventually ended their feud for good.
 * Shinji Ikari: Shinji Ikari's is refuse to do anything when dealing Evangelion Unit-03 when realized that there's a pilt that trapped inside (Toji in original anime and manga of Neon Genesis Evangelion while Asuka in remake), provoke his father Gendo to activate his Eva's dummy system against his wishes that resulting Bardiel killed with its occupant injured/killed. However, the true was when hoping he can improved his relationship with his father Gendo, as ever since Gendo abandoned him, they have doomed to can never rekindle whatever family relationship that they had.
 * Edward and Alphonse Elric: A that started it all: Edward and Alphonse tried to performed alchemy to revived their deceased mother, but something went wrong which resulting Edward loses one of his arm and his leg while Alphonse lost his whole body that his soul embedded on a huge suit of armor to keep him alive. That is what started their journey for potent Philosopher Stone to undo damages that done to their bodies as well as made them sensitive about it. In fact, Edward would extremely angry toward alchemist whom went the path (breaking laws of alchemy) that made them suffer but indifferent with error that they done and even take pleasure from it, such as Shou Tucker.

Live Action TV

 * Dean Winchester: Threatened his brother Sam that he would sever their bonds and walked away from his life as means to convinced him not to drink more demon blood and abandoned Ruby so Lucifer won't free, but backfires with Sam became succumbed with her influence. When Dean decided to rekindle their relationship, he was unable to prevent Sam from freed Lucifer.
 * Castiel believed that he doesn't need Winchesters' help when tries to settle things right in Heaven since many angels prefer to start-off apocalypse, he resort to seek the cooperation from demon for the gateway of Purgatory, kills several angels whom happened to be in his way, and absorbs every single one of souls in Purgatory to put an end of the civil war. He even decided to took over God's role over the management of the universe, only to realized that Leviathans, whom he accidently absorbed, used him as means to entered Earth and killed him from the inside.
 * The Undertaker: Has made a tragic mistake after he kills his parents in the fire house and almost costs the life of his brother Kane, which causes him to force Paul Bearer to tell the truth to find out that Kane is still alive to teach him an lesson.

Video Games

 * Amy Rose sometimes mistake other Hedgehogs for Sonic, like Shadow and Silver, except for Sonic in his Werehog form, and Classic Sonic from another dimension.
 * Reasons why Kessler, Cole's alternate future self goes back in time to hardened his past self's life was due to his where he chooses to flee along with his family when The Beast emerges and killed all life in spite the fact he actually have powers to fought him, resulting Kessler the last lifeform on earth due to The Beast's rampage.
 * Dante Aligheri: Though his actions heinous enough to be considered as MEH, it's actually a that led Dante to redeem himself over the course of his journey in Hell to rescue Beatrice where the said mistakes are:
 * Having an affair with a whore that made him betrayed his love for Beatrice,
 * Allowed himself to be misguided by priest whom falsely claimed that his soul won't be damned during Crusade (the said priest's claim later revealed to be false due to killing is always a sinful act)
 * Angrily and selfishly killed captured non-Christian prisoner of war whom intended to be held for negotiation.
 * Tal'Set: After defeating the Campaigner, Tal'Set goes into a dream state where he and the other Turoks discuss from all times of period of the Chronoscepter's fate. He throws the weapon on the active volcano, so no one could use it. However this cause a violent earthquake all across through the Lost Lands and it awakens an evil entity called the Primagen from it's slumber.
 * Tifa Lockhart: She regrets of letting Aerith to rescue Barret's adopted daughter Marlene, allowing Shinra to capture Aerith.

Literature

 * Seerow: the Andalite Prince whom feels pity on Yeerks, parasitic slugs whom can only see, hear, or interact with their surroundings when possessed a creature, provided them Andalite Technology in hopes of making their life better. This unfortunately led the Cataclysmic event called Seerow's Kindness, where the evil Yeerks emerges and began their crusade for enslaving all lifeform as much as they could in the entire universe.