One of the more common causes of mistakes, both in Real Life and fiction, is anger. No one is safe from the tendency to act like idiots once they lose their cool. There is a good reason why the word "mad" can mean both "angry" and "crazy".
Some characters lose any and all sense of rationality once their temper flare up. They will grab the Idiot Ball and not let go, as if it was made of superglue. Their actions will make things better for the other side, to the point that in severe cases, the other side only needs to sit back and watch the berserk hero/villain be done in by his/her own wrath.
Is the direct inverse of Enraged by Idiocy, where anger is caused by idiocy instead of causing it. Furthermore, it is also the direct inverse of Unstoppable Rage, where getting angry leads to badassery instead of stupidity. Likely to show up as a Fatal Flaw, especially if the character is Hot-Blooded or has a Hair-Trigger Temper. Has some overlap with Revenge Before Reason (it's not uncommon for vengeance to overlap with anger, after all) and It Seemed Like a Good Idea at the Time. See Alcohol-Induced Idiocy for another element that causes people to act irrationally. When a character intentionally invokes this in order to make their opponent slip up, that's Blinded by Rage. Sub-Trope to A Tragedy of Impulsiveness; specifically, this trope covers impulsiveness caused by anger.
- Attack on Titan: When Eren gets eaten by a Titan, Mikasa enters Tranquil Fury mode and orders her team on the offensive, despite clearly not having enough fuel in her 3D-maneuver gear to complete the attack. Only the appearance of the Rogue Titan saves her from getting eaten herself.
- Fullmetal Alchemist: Envy, while trying to negotiate a truce with Edward and Ling, unthinkingly calls the former "pipsqueak". Ed attacks Envy which leads to all three of them being sucked into Gluttony's Black Hole Belly.
- During the Infinite Crisis, this is what lead the definite FaceHeel Turn (closer to a FaceMonster Turn actually) to Superboy-Prime. His foolish actions during the Crisis Crossover cause great damage to the entire story and lead to his final Heel turn. A good example of this is when the Teen Titans tried to save Superboy from his beatdown, murdering every member that tried to get away from him with no intention to kill them at first.
- In Amazing Fantasy, Bakugou is so insistent on trying to beat the crap out of Izuku during combat training that Jirou easily leads him into an ambush. After getting himself free, he's so pissed off at Jirou that he quickly beats her into the ground when given the chance... only for Izuku to again ambush him from the ceiling while Bakugou was busy.
- In Lady and the Tramp, Tramp is alerted by Lady's barking that there's a rat in the baby's room. Since Lady is chained and can't deal with the rat herself, Tramp goes in in her stead to kill the rat before it can harm the baby. Aunt Sarah doesn't see the rat and angrily calls the pound on Tramp, mistakenly thinking he was trying to harm the baby. Jim Dear, Darling and Lady find the dead rat, and from there, it's a race to try to exonerate Tramp before the pound euthanizes him.
- In Kung Fu Panda 2, after being defeated, Lord Shen attacks Po with a dagger, not realizing that in doing so he's also cutting the ropes holding up his cannon. He is standing right under it just as the last rope gives way, and has barely enough time to Face Death with Dignity as the cannon falls and crushes him.
- In Tarzan, Clayton gets tangled up in vines as he chases after Tarzan up in the trees. He angrily starts hacking them apart, not noticing that one of the vines is wrapping around his neck. Tarzan tries to warn him, but it's too late; the vines give way, Clayton falls ands ends up hanging himself.
- In Babe, savage dogs attack the flock of sheep and kill one of them. Babe nuzzles the dying sheep in concern and budding grief, getting blood on his snout. Farmer Hoggett finds Babe bloody-snouted next to the by-now-dead sheep, and with no sign of the dogs, assumes Babe was the sheep-killer. As pigs are omnivorous, that isn't an entirely unreasonable assumption for Farmer Hoggett to make, though the odds of a young piglet doing so are very dubious. In the heat of the moment, feeling strong negative emotions about losing his sheep, Farmer Hoggett leads Babe to a place where he can tie Babe up and shoot him. Fly interferes, stalling for a few precious seconds, long enough for Mrs. Hoggett to deliver the news that the police telephoned her about savage sheep-killing dogs, thus exonerating Babe Just in Time.
- Descendants 3 has Mal thinking of closing the island off for good, trapping people there, to protect Auradon. After she and her friends team up to defeat Audry, the truth comes out. Celia, who wanted to be able to visit her father Dr. Facillier, got so angry she threw Hades' Ember into the water, destroying it, and leaving herself and the others defenseless.
- Avengers: Infinity War: Iron Man's team has managed to restrain Thanos when they learn he had sacrificed Gamora's life to obtain the Soul Stone. An enraged Star-Lord lashes out, which allows Thanos to break free of Mantis's empathic powers and scuttles the team's plan to take the Infinity Gauntlet from him.
- In Attack of the Clones, Anakin rushes to attack Dooku, ostensibly to avenge the Jedi slain during the battle. Dooku quickly incapacitates the impulsive charge with Force Lightning, incapacitating Anakin and forcing his mentor, Obi-Wan, to battle Dooku on his own.
- A folktale has a king go hunting with his favorite falcon and get separated from the rest. As he's thirsty, he finds a waterfall and puts his cup in it. As he's about to drink, the falcon swoops down and knocks the cup away. The king is surprised but puts his cup in the waterfall, but the falcon knocks it away again. The third time this happens, the cup is swept away downriver. The furious king starts chasing the falcon with his sword, following it up to the waterfall's source. As he impales the bird on his sword, the king notices a decomposing corpse in the water, realizes the water was unsafe to drink, and understands too late why his falcon was trying to keep him from drinking.
- There are various folk tales about parents seeing blood and chaos and jumping to the conclusion that their guard animal mauled their baby. The poor pet is slain in mistaken revenge, only for the parents to find the baby okay and a dead wild beast in the house. Thus the parents find out too late that the blood came from the wild beast that the pet had killed in the act of protecting the baby. The type of guard animal and the type of wild animal change from telling to retelling.
- One version has a mongoose tearing apart a snake and displaying himself in all his gory glory to the distrustful mother, who kills the mongoose with a water pitcher.
- Some versions have a dog killing a snake, with the father jumping to the wrong conclusion and dispatching the dog.
- Most versions have a dog killing a wolf, with the father making the tragic misunderstanding.
- Mr. Men: Little Miss Trouble's story has Mr. Clever get so offended by the lie that Little Miss Trouble (That Mr. Small had called him a rude nickname) told him that he falls for it and it leads to him attacking Mr. Small out of anger without letting Mr. Small give his side of the story.
- Warhammer 40,000: Orks and Chaos troops (especially Khornates) are prone to this:
- Ciaphas Cain once destroyed an ork Waaagh! by pissing off its warboss. Instead of letting his bodyguards dogpile the two humans, Korbul prevented them from interfering, leading to his death and the fragmentation of the Waaagh! as each nob tried to wrest control of it from the others.
- In another story, he sets up a tripwire that leaves an ork on the ground. The furious ork sees Cain's Commissar Cap hanging on a live wire, angrily swings his choppa at it, and promptly fries.
- The ork-controlled sector of Octarius is currently in a Forever War between orks and tyranids that started when the tyranids managed to infuriating the warboss into being separated from his bodyguard, quickly surrounding and killing him.
- Kharn the Betrayer got his name from an incident when both the World Eaters and the Emperor's Children Legions stopped fighting due to the intense cold, instead seeking shelter. Infuriated by such cowardice, he ran around with a flamer setting fire to every shelter and every Space Marine he saw, crippling both Legions to the point where millennia later they are reduced to small warbands. Despite the name, neither Kharn, the World Eaters or Khorne himself see it as a betrayal (Khorne demands that his followers spill blood in his name at every opportunity, no matter if it's their enemy's, their ally's or their own), and the Blood God rewarded Kharn for his deeds by making him his champion.
- Mortal Kombat X and Mortal Kombat 11: This trope describes Kotal Kahn's Fatal Flaw, as he seems to have trouble keeping his head cool when something makes him angry. To wit:
- The first time he got pissed off in the comics, he left Goro armless, but refused to kill him, forgetting that Even Evil Has Loved Ones, and then King Gorbak proceeded to wipe out the Osh-Tekk, making Kotal The Last of His Kind.
- In MKX's story, when D'Vorah betrayed him, he lets his anger against her and Earthrealm get in the way of reason, deciding to outright kill Cassie's group instead of helping them stop Shinnok, almost bringing ruin to the realms.
- It comes up again in 11 when he tries to save Jade from the Tarkatans. He gets enraged and attempts to commit genocide on them. This in turn prompts Jade to fight and defeat him, leaving him to be easily captured by Shao Kahn.
- Sonic and the Black Knight : When the Big Bad breaks Caliburn Sonic loses his cool and unleashes what, in any other context, would be an Unstoppable Rage on his opponent. Unfortunately, he's hopelessly outmatched so all he gets for his trouble is a No Holds Barred Beat Down. Yet he keeps getting up and trying again, even as his allies beg him to stop. Ultimately subverted in that, after getting beaten within an inch of his life, Sonic is able to channel his rage into the more constructive Heroic Resolve. Which proves to be the key to rekindling Excalibur's lost light: Restoring Caliburn in his true form as the legendary sword and granting Sonic a Golden Super Mode to level the playing field.
- Done in a roundabout manner in Captain SNES: The Game Masta. The incarnation of Alex's hatred is also an idiot, because what he hates most is stupid people.
- The Simpsons: The episode "Homer's Enemy" has the one-time character Frank Grimes losing it after being fed up with the antics of the nuclear plant, especially by Homer, with the last straw being Homer winning a contest aimed for children. Grimey, as Homer calls him, goes crazy and stupidly breaks all of the rules at the plant, trashing his boss, and him dying by touching the high voltage wires.