Unami, the chosen guide for Team Summer A. The members of the team are previous students of his, all whom he has bullied, physically beaten, verbally and sexually abused and overall is hated by all of them to a certain degree. One of them even said she'll kill him. And upon awakening in the future, first thing he does, he bursts into the room where they are and begins barking orders to the students that hate him, all of whom were issued guns! Of course, he ends up fatally shot and left to die alone... You can't really feel sorry for the guy.
Majority of the Team Summer A candidates. Despite being trained from birth onward to survive in nature and be self-reliant, they don't take the Final Test seriously and think it's not really dangerous. They quickly fall victim to various traps or dangers in nature, simply because they didn't use their heads.
Special mention goes to the girls who bullied Ayu. They make her go with them and use her as a sort of maid, making her cook for them every time. When they decide they want to eat something with chopsticks, they choose to make them out of branches from a poisonous tree. Despite these girls having the same knowledge about plants as Ayu, they make the chopsticks, eat and die from the poison. Did they skip class on the day they were supposed to learn about poisonous plants or something?
Aho Girl: The titular protagonist, Yoshiko Hanabatake. For all of her astronomical stupidity, which is well into Refuge in Audacity levels, it's a very good thing in her universe that she is somehow a lucky Idiot Houdini at parodically impossible levels and the story works on an exaggerated version of Rule of Funny. If realism or anything for drama were to come into play, she would literally die a billion times over.
The Animatrix: Humanity to a certain extent in the segment, "The Second Renaissance Part 2". They basically cause their own defeat by blocking the sun, without any objections and without thinking or using common sense, to try to cut off the machine's power supply, but it also kills Humanity's vegetation and it cuts off Humanity's Vitamin D (ouch), and the humans were not able to adapt to this and are ultimately defeated by the machines.
Another': Lampshaded by Matsunaga in his video tape recording of how he accidentally stopped the curse mid-year. He mentions a boy named Hamaguchi, whom he describes as not very bright, as being the only one who brought an umbrella while visiting a local shrine... during a thunderstorm.'' One has to wonder whether Hamaguchi's death from being struck by lightning was really due to the curse.
Marco Bott overhears his classmates, Reiner and Bertolt, having a very suspicious conversation about Titans. He immediately confronts them about it, making it clear that he overheard everything. They quickly panic and chase him down, at which point he attempts to talk his way out of it. They steal his gear and leave him to die, because He Knows Too Much.
As chaos breaks out in Marley and the assembled crows scramble to get to safety, Udo tries to get a piece of rubble off his fellow Child Soldier, Zofia, not noticing that Zofia isn't just trapped under the rubble — it crushed everything above her waist. He promptly gets trampled and killed by the panicking crowd.
Inverted when Randy and Pezzo's stupidity leads to them becoming immortal.
Isaac and Miria, also Too Dumb To Die, as they'd probably fly under the radar of anyone who could kill them.
Not that they'd be able to anyway; it takes them until they're walking around the modern-day world to realize they haven't aged in about 70 years, and are thus also immortals.
Only immortals can kill immortals, and other immortals will either let them live because they are friends, because they find them amusing, because they underestimate the chaos they bring or because they are truly terrified of the after-effects they'd suffer from said killing.
The torturer of the Tower of Rebirth. Thinking that he has the upper hand because he locked the most dangerous enemies of his kingdom (aka the main characters) in a dungeon room, he proceeds to hang around to taunt them. When Guts slowly stands and asks in an unnervingly quiet and soft voice if he was responsible for Griffith's mutilation, the torturer pays no heed and proceeds to describe exactly how he tortured him over the past year, finishing by showing them his crowning jewel: Griffith's severed tongue, worn as a necklace. His death is brutal, quick and horrifically painful. Worse, he brags how nothing they do will succeed, because the door is three times thicker than any normal door. Too bad he never took Guts' weapon of choice into account...
Wyald, demonic Apostle and leader of the Black Dog Knights sent after Griffith and the Hawks by the King of Midland, had one thing he wasn't allowed to do: do not kill Griffith, the man destined to become a member of the God Hand. Three guesses what he tries to do. When he defends his actions to Zodd, a much stronger Apostle in the process of impaling him, he claims that the main directive of Apostles is basically "you can do whatever you want to whomever you want," and therefore his actions were perfectly fine. Zodd takes these words to heart, and declares that what he wants to do right now is rip Wyald to pieces for his insolence and stupidity. He proceeds to follow through.
Black Bird: Misao What-Are-Warning-Bells Harada seems to have a death wish. She knows full well she's being targeted by an entire realm of demons who, best case scenario, want to eat her, but again and again she simply cannot stop herself from following powerful demons into isolated locations in the hopes that they'll give her some information about Kyo, and is actually surprised when it inevitably doesn't end well.
Chaka, not only the biggest asshole in the series, but also the biggest dumbass as well.
Thinking himself to be the baddest ass of them all, he obnoxiously hits on Revy in an attempt to get her to duel him, then beats the crap out of Rock in order to antagonise her enough to draw on him, until he gets dragged off by Yoshida. This, despite the fact that Rock and Revy are working for Hotel Moscow, whom his bosses are trying to conduct important negotiations with.
He decides to take over the group by kidnapping the heiress to the leadership of the clan with the help of a street gang, and holding her hostage in order to draw out Ginji, her katana-wielding,badass protector, to kill him before selling the girl into sexual slavery. Predictably, Ginji and Revy tear the Mooks apart, whilst Chaka exits, dragging Yukio with him (and loses her after Rock blindsides him with some cleaning fluid, a bowling pin, and a "Fuck You!").
Later, he comes across Revy again, and again tries to get her to draw, because clearly he can take the woman who just tore through his entire crew like they were nothing. He starts counting down from ten... and she doesn't wait, and instead drop-kicks him in the face and delivers a "The Reason You Suck" Speech, before luring him to a nearby pool... where Ginji is waiting for him to deliver an extremely nasty, but very, very Karmic Death.
Rotton the Wizard seems like this at first, with his In the Name of the Moon spiel at his introduction, during which Revy shoots him. Subverted in that he's the only one who bothered to wear a bulletproof vest. And his current position as a maybe-Morality Pet to a Dragon Lady knife-wielder and a Chainsaw Good body disposal expert.
The Neo Nazi who stops to brag about how awesome his Hand Cannon is. While the vicious, murderously psychotic Dark Action Girlwho effortlessly slaughtered his fellows is standing right in front of him, and not only has her weapon drawn, but is taking the time he's shooting his mouth off by reloading the weapon. Needless to say, he gets blown away mid-rant for his trouble.
The Neo Nazis in general were this. They knew that there was another armed group in the area after the same painting that they were. What did they do after retrieving the painting and driving the Lagoon company away? They started to party. Loudly. With plenty of alcohol and not even a single guard posted. While they had a large supply of firearms on hand. Really, even without Revy and Dutch the idiots stood a good chance of accidentally shooting themselves up before the night was over..
Chen and Louvac are both this. Chen decides to hire Louvac to kill the Lagoon Company traders for working with Balalaika, then proceeds to brag about it to everyone in town, completely ignoring that not only is the Lagoon Company successful for being very good at what they do, but that said skill has earned them a lot of friends in high places, up to and including Balalaika herself, who deals with him by rigging him with C-4 and making him go boom.
Louvac and his men not only try to take on Revy (a badass of such renown in Roanapur that her presence bumped a bunch of mercenaries' price for a job from $1,000 to $30,000), but they try to shoot up the Lagoon Company's boat from both sides... without staggering their positions, causing two of the boats to take each other out when Dutch hits the brakes and puts them in each other's fields of fire.
In the anime adaptation "El Baile De La Muerte" arc, Roberta unfortunately gets dangerously close to this trope when confronting Caxton's Gray Fox teams. While Roberta chewed through the Roanapur locals with ease, who were at best retired military kitted with surplus equipment, Gray Fox is an elite spec ops team with the latest technology and years of combat experience that makes most of Roanapur look like toddlers, and had at that point come to blows with the main cast three times and came out relatively unscathed. Roberta holds her own, but by the time Garcia and Rock unleash their gambit to make her give up, Gray Fox has run her through the wringer and crippled her for life, and they did this while they had orders not to kill her. By the end of it, it is ambiguous if Garcia's stepping in saved Gray Fox from Roberta, or Roberta from Gray Fox.
Driscoll boasts about killing Sasakibe to Yamamoto's face, then rubs it in further by using Sasakibe's stolen bankai against Yamamoto. Yamamoto's response is to fry Driscoll to the bone.
A captain is more powerful than the rest of his division (200+ warriors) combined and all shinigami know to stay well away from fighting captains as a result. When the Tenth Division captain accidentally crosses jurisdictional boundaries, a patrolling 13th division soldier runs over to protest, completely ignoring the fact the intrusion has happened because the captain is being pushed back by a captain-class enemy. The soldier is very quickly killed.
Sakura is this way around Sabato, always offering her a hand even when she had tried to kill him just seconds prior or allowing her to seduce him in her attempts to kill him. Her logic is, if she kills him, Dokuro can't. The eponymous Dokuro is an angel who can turn back time, meaning Sakura dies and then time is rewound to when Dokura wishes it to be.
Bokurano: As the story goes on, thousands of people die in Zearth's battles as a result of collateral damage, and many people who have lost loved ones seek revenge. Junji "Katari" Karita, in an attempt to delay his parents' divorce, gets the brilliant idea to falsely claim to be one of the pilots on live TV, helping a rival TV station scoop Akira Tokosumi and the others. Not long after Katari admits this, a security guard shoots him dead, having gotten a gun from a support group for Zearth's victims.
Case Closed: One murder victim had a bet with his friend as to who would die first, with each man naming the other as a beneficiary in his life insurance policy. It clearly never occurred to the victim that this would be the perfect incentive for his "friend" to murder him in order to get a lot of money.
Cross Ange: Julio proceeds with his extermination campaign, even when he was forewarned early by the other Mana leaders not to. He provokes the Tranquil Fury of Embryo and gets a twin Wave-Motion Gun attack to the face.
Darker than Black: Goran, the Russian Contractor in the second season. He's got Super-Speed with none of the Required Secondary Powers. His reaction times aren't enhanced, he's not superhumanly tough, heck, he even gets sore muscles. He is defeated by a contractor whose power is to make it rain, because his superspeed made each raindrop hit with the force of a bullet. He also doesn't carry a weapon of any sort, meaning his offensive options are... well he's got none. Any attempt to punch or grab his opponent would liquify his arm.
Raye Penber, an F.B.I. agent who was sent in to shadow Light Yagami, as a potential suspect for Kira. Due to circumstances, Raye is forced to get into contact with Light... and proceeds to show his real ID to his target, who he is following, because he is under suspicion of being the one who is killing people from afar. How could this possibly backfire? So, Light proceeds to memorize his face and name and manipulates him via the Death Note into helping him kill the other agents sent to Japan, before letting Raye die from a Death Note-induced heart attack.
Naomi Misora, the fiancee of the above-mentioned, recently murdered an F.B.I. agent, figures out crucial information on the Kira case and then decides to trust Light with it after he's been acting creepy, following her around, and asking "Have You Told Anyone Else?" Incidentally, she decides to trust Light because he reminds her of L.
Demegawa, a slimy little man who uses the name of Kira to pad his own pockets, knowing that Kira is a vengeful god of justice without much sense of mercy. He and his circle become the first victims of Light's hand-picked Fourth Kira, Teru Mikami, who gives them all the "sakujo" treatment after Light gets fed up with him.
Misa Amane. After having her life extended twice by two shinigami, she then goes and cuts her life in half twice, by doing the "eye deal" again. Due to life shorting, she later commits suicide.
Light himself falls victim to this at the end of the manga. When he's exposed as Kira and shot by Matsuda—the last person he expected to turn on him—in his desperation, he makes the serious mistake of begging Ryuk to write down the names of everyone else in the room, forgetting that Ryuk is on no-one's side and doesn't care who wins as long as he's provided with entertainment. Ryuk, who had expected Light to think of a way out of his predicament, realizes that Light can no longer give him the entertainment he craves, and writes down Light's name in his Death Note instead. Averted in the anime, where Light escapes—gravely injured—to an abandoned warehouse, and Ryuk writes his name in his Death Note as a Mercy Kill, because Light will either die or be sentenced to life imprisonment anyway.
The newbie party that Team Touden run into are almost completely wiped out by a basilisk. When their leader is running from it, he turns his back and it kicks him with its poisoned spurs. Laios remarks that turning your back on a basilisk is asking to be killed. Needless to say, the last two members only survive because Laios and Senshi save them.
Kabru's party find a box of treasure and immediately start playing with the coins and wearing the jewelry. This despite the fact treasure bugs are a well known dungeon hazard. They all end up paralyzed and have to be rescued by a team of corpse hunters.
An unnamed demon slayer barges in on Tanjiro's confrontation with Rui, arrogantly boasts that he can kill a kid-like demon easily and refuses to listen to Tanjiro's warnings that Rui is more dangerous than he looks. Rui simply dices the top half of the demon slayer's body once he charges at him without even bothering to look in his direction. Even if the demon slayer didn't know that Rui is one of the Twelve Kizuki, he really should have known better than to think he can just charge at an unknown enemy and live to tell about it.
While Kamanue at least had the excuse of not knowing that Muzan can read their minds when the latter decides to massacre them for being too weak, Mukago and Wakuraba are aware of this, but Mukago futilely tries to deny Muzan's accusation of cowardice and Wakuraba attempts to escape the Infinity Castle, a location he is unfamiliar with and knows is controlled by Nakime. Emnu even lampshades the latter's foolishness.
Omitsu, manager of the Kyogoku House of the Yoshiwara Entertainment District, attempts to confront Daki with a hidden knife upon realizing she's not human, failing to take into account that Daki's cruelty would make her more than willing to capture and murder her almost immediately. Daki even lampshades Omitsu's foolishness with her Evil Gloating.
Jun gets Episode 1 going by encountering a strange woman (Asuka) stalking her. When Asuka comes to her door in the middle of the night, Jun, despite being afraid, unlocks her own door, willingly gets in a car with Asuka, lets Asuka drive her to a darkened area of the docks, and obediently walks into a deserted warehouse whereupon Asuka locks her in with a werewolf. Jun in general is prone to acting like this by obediantely doing whatever other people tell her unless she activates her Superpowered Evil Side.
Also, Jun's girlfriend Kazumi dies when she leaves her hiding place for no good reason whatsoever.
Every single government in Dragonaut: The Resonance. One side commits several outright acts of war, which the other side ignores. The same government then kidnaps one of the dragons, which causes the hive mind of the dragon's homeworld to launch an attack which destroys a space station, and a battle which wrecks most of Mars. Who does ultimate blame get placed on? The rescue party. And in a separate incident, a clearly insane dragonaut attacks another dragonaut over a perceived slight at the spaceport. While a shuttle is launching. When he misses a shot, trashing part of the launch equipment (nearly getting all the other dragonauts killed, as they are in the shuttle), he blames his target for dodging.
Goku's father Bardock from the prequel OVA Dragon Ball Z: Bardock - The Father of Goku, who knows far in advance that Frieza is going to destroy his home planet. What does he do? Thanks to a double dose of both Honor Before Reason and Revenge Before Reason he decides to take on Frieza single-handedly in a bid to stop him from destroying Planet Vegeta, despite knowing perfectly well that he was FAR too weak to stand a chance in hell against Frieza instead of getting in the nearest pod and getting the hell out of dodge and maybe coming back when he did stand a chance. To be fair, Saiyans aren't exactly known for strategic retreats.
Garlic Jr. from Dragon Ball Z: Dead Zone is this in spades, as when he ends up fighting Goku and Piccolo in the climax and has them on the ropes, instead of just wearing them down with his immortal stamina he chooses to open a portal to the eponymous Dead Zone, which he is promptly knocked into by Gohan.
Later on in the series, Garlic Jr. returns, only to try the exact same thing. Keep in mind again: Garlic Jr has Complete Immortality. He could defeat literally anything in the universe by just wearing it down. He went for this solution twice. And since his return was only made possible by the Makyo Star (which is destroyed), the second time meant he was gone for good.
In Dragon Ball Z Abridged's take on it, the plot of Dead Zone is a script Krillin is pitching to Nappa. When pressed on the issue, Krillin admits that he wrote himself into a corner. Funny enough, this trope isn't so much in place, as Shenron responds to the wish by saying that he can't wait to see how Garlic Jr. manages to blow this. Played for Laughs when he returns and tries it again, with him screaming in frustration that he did the exact same thing that made him lose last time.
During the Frieza Saga in Dragon Ball Z, one of Frieza's Mooks comes in while he's berating Zarbon and confirms Frieza's suspicions that Vegeta had attacked a Namekian village and made off with a Dragon Ball. Unfortunately, he makes the critical mistake of admitting to Frieza that he killed the sole surviving Namekian without bothering to ask him where the Dragon Ball was, and gets vaporized for it.
Frieza: You imbecile. You've disposed of the only witness.
Frieza has been sliced in half, near dead, and was given a sliver of Super Saiyan Goku's power to survive on as an act of mercy. And what does he do with it? He tries to use it to kill the Super Saiyan from behind, despite the fact that it most likely wouldn't have made a dent. Needless to say, it doesn't end well for the tyrant. He got better, only to get Killed Off for Real by Future Trunks. It's even worse when he comes back in both Dragon Ball Z: Resurrection 'F' and its Dragon Ball Super adaptation — after being resurrected, his men tell him to just leave Goku and just deal with his empire instead. Instead Frieza decides to train, get stronger and go try to kick Goku's ass again. Predictably he is beaten again and killed again. Even though Frieza was smart enough to acknowledge Goku's victory of Majin Buu and train enough to be even stronger than Goku, he neglected to train his stamina properly. Goku wore him out even faster than their first battle.
In fact, in Super, he decides to try and piss off Goku again, targeting his friends and trying to kill Krillin once again to deliberately enrage him, despite knowing full well from the last time what happened when he pushed Gokupast thebreaking point. One wonders by this point if Frieza being knocked around on Namek gave him brain damage or something.
Just to add some hypocrisy into the mix, he repeatedly mocks Goku and Vegeta for their arrogance, despite the fact that his own arrogance was not only the cause of his downfall, but he's continuing to act arrogantly.
Vegeta, to some extent. He has the bad habit of throwing furious raging blasts at his enemies that are often powerful enough to blow up a planet. However, Saiyans can't breathe in space, which means he would also die! Of course, Vegeta would rather die than lose, but he never even considers this detail, even when others scream it at him. This is also rather foolish behavior in that it tires him out quickly, which is how Frieza deals with him after transforming into his final form.
Also, he let Cell absorb Android 18. That was arrogant to the point of sheer stupidity.
When Dr. Gero created Androids 17 and 18, he turned two rebellious teenagers into fighters stronger than himself. He also left their human brains and therefore free will intact, leaving them uncontrollable and unpredictable. Then he converted himself into an android, only to base his own design on the weaker energy absorbing model. Not content with that level of suicidal behavior, he continues to berate and threaten them after waking them up as a desperate Godzilla Threshold measure despite the fact that they've already tried to kill him once before, and continues doing this even after they snatch the killswitch remote control from him and he loses all his control over them. His death came quickly after. For an evil "genius", he's not too bright, at least not when it comes to dealing with rebellious teenagers.
Androids 17 and 18 themselves. Despite Android 16, Piccolo, Krillin, Trunks, and Tien all warning them to run from Cell while he's distracted, repeatedly, both of them stayed, with 17 even arrogantly believing he could beat Cell by himself before he was absorbed — after being beaten so badly by Cell he could barely stand, no less. His sister is no quicker on the uptake, though, standing around gaping even after Cell absorbs her brother, to the point where 16 literally has to grab her to try and make their escape (for all the good it does at that point).
Babidi bosses Majin Buu around, abuses him both physically and verbally (especially Buu's intelligence), and the only thing he has to keep Buu in check is repeated threats to seal him up again. The problem being that releasing Buu was Babidi's entire plan for millennia, meaning it was obvious he wouldn't re-seal Buu after all that time and effort, and Buu's Healing Hands powers were the only thing offsetting Babidi's Squishiness. After Goku plants the seeds of rebellion by asking "Why do you let him treat you so poorly?", Buu grabs Babidi by the throat (keeping him from casting the sealing spell), calls him an idiot, and then punches his head off.
Worse, Buu had been covertly trying to kill him for a while before Goku accidentally gave him the idea on how to kill Babidi without getting sealed. Babidi should have really treated Buu better...
Babidi also has a tendency to kill his minions when they’re no longer of use to him. This comes back to haunt him when Buu decides to kill him and there is no one to save him from death.
During the Buu Saga, Chi-Chi walked up to Majin Buu and slapped him while yelling at him for killing her oldest son (who was leagues more powerful than her by dint of being a Super Saiyan 2). While this was a perfectly understandable Mama Bear reaction, she still got turned into an egg and smashed for her stupidity.
Dragon Ball Super: During the Future Trunks Saga, Gowasu goes to the future in an attempt to talk Zamasu/Goku Black down and give him a Last-Second Chance at redemption, ignoring the fact that Black has already killed twodifferent iterations of him to advance his Zero Mortals Plan; only Goku and Vegeta's intervention saves Gowasu from being vaporized when Black refuses. It's even worse in the manga adaptation, where Gowasu decides to try to reason with Black without Goku and Vegeta backing him up, leading to Black stabbing him in the chest.
Durarara!!: All the gangs in the city of Ikebukuro have Rule #1: Don't screw with Izaya Orihara. However, the entire city has Rule #0: DON'T SCREW WITH SHIZUO HEIWAJIMA. The gangs in the city don't bother telling members the latter rule, since if you're dumb enough to break it, you're probably doing the gang a favor by getting yourself killed. This rule is prevalent that anyone who doesn't follow it is regarded as less intelligent than a public school dropout. Just about the only exception to it is the aforementioned Izaya Orihara, one of the few men capable of fighting Shizuo without facing major injury — the two outrightdespiseeach other, and Izaya makes it a habit to piss off Shizuo whenever he can, mainly because he can get away with it (though not for lack of trying on Shizuo's part).
The female assistant in the first episode. The moment she saw the devastation that was being caused you would have expected her to realize that a noncombatant like herself should do the smart thing and get to the exit ASAP.
Most of the guards in the first episode who are massacred by by Lucy also fall in this category. Despite knowing about the vector range (2 meters) they choose to stand still as slowly walking death approaches.
Mirajane and her not quite dead little sister Lisanna are battling Azuma, a Blood Knight opponent who appears disappointed by his two supposedly weak opponents until Lisanna boasts that Mirajane is the famed "She-Devil" Mirajane who only becomes strong when using her Satan Soul transformation (which Mirajane clearly said she is refraining from using because she's low on magic power). So Azuma makes Mirajane do just that...by strapping Lisanna to a bunch of explosives and giving Mirajane three minutes to beat him before they explode, which leads to Mirajane making a Heroic Sacrifice to save Lisanna from the blast. So Mirajane, one of the strongest fighters at Fairy Tail's disposal during a time when they need as many strong fighters as they can get, nearly gets herself killed thanks to her sister's underestimation of their opponent. Fortunately for Lisanna, she realizes just how stupid it was of her to do that and wises up.
Something similar happens not long after, though in this case, it's more like "Too Dumb for Everyone Around Her to Live". Before Grimoire Heart came to attack, Fairy Tail was in the middle of an exam that Cana was taking very seriously to the point that she threatened to leave the guild if she failed. So what's the best thing to do when a bunch of uber-powerful opponents have come to fight, inadvertently interrupting the test in the process? According to Cana at the time, it's continuing to take the test as if there weren't any enemies to begin with, instead of helping her friends fight when some of them are falling left and right. To her credit, she didn't realize that some of her friends have already fallen, but what does she do next? After Lucy gives her a lead on how to pass the exam, she knocks out Lucy and abandons her to do just that. And this is while knowing that there are enemies powerful enough to kill them wandering around. And Lucy would have been killed if she hadn't woken up at the last possible second. Again, to Cana's slight credit, she did try hiding Lucy out of sight from potential enemies. But that didn't stop Lucy from being found anyway. Similar to the above example, however, Cana eventually recognizes her own idiocyand rushes to her friends' rescue.
The Tartaros arc features the titular guild, whose members are legitimate demons, trying to activate a powerful magic. To unlock this magic's seal they need to kill certain members (current and former) of the Magic Council, but don't know which ones, so they just opt to kill them all until they succeed. There is one, however, who is subverted to their purposes and helps them find the last former member with a seal. To save the trouble of tracking him down, the traitor takes the last part of the seal into himself, with the intent to give it to someone else so they can be killed and break the seal. He tells Tartaros' members this after taking the seal but before passing it on. A group that has a necromancer within their ranks, meaning he has no more value to them alive than dead in the first place. He's immediately Rewarded as a Traitor Deserves.
The anime adaptation of Fate/stay night [Unlimited Blade Works] shows off Caster's original master, Atrum Galliasta, who was killed by her before the events of the visual novel. It doesn't take long to become apparent why: Atrum openly bragged to Caster about how amazing his technique for converting humans into mana crystals was, at which she then created a larger and more powerful mana crystal with no effort whatsoever and asked he stop murdering innocent women to make them. His response to this was to physically assault her while making misogynistic remarks, then spend a Command Seal on ordering she not harm him. It is perhaps worth noting at this point that not only had Caster just casually wielded magic far beyond his, but Caster is actually Medea—that is to say, one of the most famous examples of Mistreatment-Induced Betrayal and Woman Scorned in all of fiction, who, within the story, is titled "The Witch of Betrayal", who is particularly opposed to harm done to women, and who currently possesses a magic dagger capable of undoing magical commands, bonds, and contracts. Only a short while later, she uses said dagger on herself to break their bond and the Command Seal, and then murders him.
Fist of the North Star: One would think that after running into a guy who made several of their comrade's heads explode by poking them a few times, the survivors would then decide to cut their losses and take up a career other than banditry, or at least try their hand at banditry someplace where the guy who is making people's heads explode isn't. But instead they invariably double-down and seek revenge against Kenshiro for daring to kill their comrades and/or interrupt their acts of pointless cruelty, a decision that invariably results in Kenshiro getting within arm's reach of them, at which point he pokes them in the face and their heads explode. This happens repeatedly with minor villains across the series.
Deer-Horses in The Fruit of Evolution cross into this from Fragile Speedster. They are renowned for their incredible running speed... but are equally renowned for their fragility, timidness, and stupidity. To the point they literally need to be reminded to breathe and if left unattended for too long may simply suffocate. They also have a tendency to drop dead at the slightest impact or shock. Whilst their defenders try to champion them as Difficult, but Awesome, they are widely regarded as the most pathetic choice of mounts in the world. When about a dozen adventurers try to take place in a yearly racing tournament riding them, not one deer-horse makes it over the starting line, as they all forgot to breathe and suffocated before the signal to start.
Shou Tucker's infamous decision is almost as idiotic as it is despicable. So he creates a talking chimera, using a human being as one of the two creatures fused to make said chimera. If anyone knew, he'd be executed, and not once does it cross his mind that a chimera that can talk...can talk. He gets incredibly lucky with his first chimera; the only thing it says is "I want to die." So, what does he do? He makes another one! And this one does tell on him. Worse, rather than finding someone who wouldn't be missed, he uses his own daughter! Even if she hadn't revealed the Awful Truth to the Elric brothers or if Edward hadn't figured out the entire truth, the chimera would have drawn attention and someone else would have suspected Nina's disappearance and put the piece together.
In the manga version, several members of the Amestris military give Zolf J. Kimblee a Philosopher's Stone so he can test it to see how much more powerful he gets. Kimblee uses it to create massive destruction, upon his return they ask for it back, and Kimblee does what everyone who has spent 5 minutes with the man expects. He swallows the stone then kills the morons who gave arguably the most psychotic person in the series (only Envy is as close) a stone that upgrades his power. Maybe next time they should do some research on the guy they use for their experiment.
Kimblee later suggests that he faked being sane in order to pass the State Alchemist exam. Perhaps everyone except the Homunculi and those in on their plan was fooled.
Dietlinde Eckhart, the main villain of The Movie. She invades Amestris on the mistaken belief that it's Shamballa, which it shares no similarities with, and doesn't even make sense. Shamballa is supposed to be located near Tibet, and Amestris is in another dimension. She then tries to take over the place when the Thule Society has only about 1,000 members while Amestris is a heavy militarized nation with a much larger army. Her army is crushed in about 15 minutes.
Envy went on a huge rant about how it was the one who killed Roy Mustang's best friend Maes Hughes, and almost hurt itself from laughing about it. Envy went out of its way to tell how it was also the one who started the Ishval War and how amusing it was to see such a huge battle over the death of one little girl that it killed. Envy finds itself getting its eyes burned off two seconds later by Roy Mustang. Good for Envy it can heal. But then, Envy doesn't know when to call it quits, pushing its luck one too many times by attempting a Shapeshifter Guilt Trip on Mustang by taking the form of Maes Hughes. Mustang responds by blasting Envy with his strongest fire attack so many times that Envy's Healing Factor is overtaxed.
Fushigi Yuugi: Miaka. Though Miaka doesn't actually die in this series, that is not due to lack of effort on her part. Time and time again, she runs headfirst into danger alone, despite not having any magic or compbat skills, and despite having 7 guardians whose sole purpose for existing is to protect her. She survives only because of the Suzaku 7 wage a vigorous battle with darwinism to keep her alive and the fact that most the enemies just want to kidnap her instead of kill her.
The Empire thought it was a good idea to attack the Ginza district of Japan full of unarmed, innocent civilians (with the exception of the local Police, but the regular Police wasn't enough to stave them off effectively), while they obviously had the advantage initially, that was abruptly brought to a cold stop once Japan properly countered by sending in the JSDF with their modern tech, smashing their medieval tech and swiftly ending their unjustified bloody invasion and securing the other side of the Gate to prevent another atrocity in Ginza's streets from happening again.
The big mistake was when the Empire engaged the JSDF at the Battle of Alnus Hill. While the initial Imperial invasion of Japan could be justified by not knowing what was on the other side and assuming that unknown means threat, by Alnus Hill they knew that their opponents had a technological advantage and a fortified position and they attacked anyway.
Zorzal El Caesar, second son of Emperor Molt and Crown Prince of The Empire, This guy is an asshole and rapist who believes he can take on the JSDF and win despite the fact the latter has far superior tech. The first thing he does once he takes the throne? Have his goons smear the JSDF's name by disguising as them and attacking the Alnus Living Community.
Guardian Ninja Mamoru: The very premise of the series: a family has been secretly protected for ninjas for so long that they've lost the ability to survive normal life. The latest descendant, the female protagonist, therefore has a supernatural ability to walk blindly into trouble, and generally gets rescued before she even realizes what's happening.
Gundam Build Fighters Try: Team Try Fighters are going up against Team Angelfish, a group of Gunpla Fighters who do an aquatic theme as they're also part of the swim club. As the battle starts, Team Angelfish make note that all they had to do in their terrain, Tundra, is break through the ice, dive in, and give Team Try Fighters trouble. However, as the ice is frozen solid, they panic and decide to self-destruct instead of allowing a Curb-Stomp Battle. What makes it this trope is the fact that they gave up so easily. Their suits were a Z'Gok, Gogg and Zock, which were designed for aquatic landing, meaning they were good for both water and land. All three of them also had dangerous weaponry, especially the Zock, who had beam-type weaponry in front, behind and on top. They essentially took Crippling Overspecialization to a new art form.
In Hell Teacher Nube, more than a few students mess with the supernatural, failing to realize that Evil Is Not a Toy. But usually, after Nube bails them out, they learn their lesson and let sleeping monsters lie. But no matter how many times Miki finds her life in danger after playing with forces beyond her control, and she always does, she never stops. Once she graduates out of Nube’s class and he isn’t around to protect her anymore, you can bet her life expectancy will be very, very short.
Luke Valentine. Jan at least knew there was a good chance the attack on the Hellsing Organization would turn out to be a suicide mission and just didn't care, but Luke really thought he would be the one to kill Alucard, despite clearly having done no research on what Alucard was truly capable of. He ends up dying in sniveling terror.
In the Cross Fire omakes, a cult honestly expect Heinkel and Yumie, who they (correctly) believe to be Vatican assassins, to leave simply because the cultists insist the church is a holy site. The same assassins that are there because members of said cult launched a chemical attack on the Vatican and tried to assassinate the pope and then publicly took credit for the attack. Naturally, Heinkel and Yumie kill all of them.
Zorin Blitz explicitly disobeys orders from The Major to not attack Hellsing HQ until the main forces arrive due to Alucard and Seras being the organization's trump cards. While her attack does end up killing Pip and almost all of the Geese, she proceeds to gloat and mock Pip's death as being in vain instead; this only infuriates Seras, who drinks his blood and becomes a true vampire. Seras then proceeds to use the power that Zorin inadvertently granted to her by murdering Pip to brutally and viciously destroy her. The Major doesn't even dignify Zorin with a suicide chip activation because of how badly she fucked up by disobeying him.
Right, Keiichi, go into that creepy basement with a self-confessed psychotic murderer. And after you survive that, feel free to go out in the dead of night to chat with her. note To be fair, the original game had a decent reason. Doesn't make it any smarter, though.
Earlier, at the climax of Onikakushi-hen (at least when viewed through the eyes of someone who isn't steadily going insane) Rena and Mion contract a bad case of the lethally stupids: their friend Keiichi has recently become surly, withdrawn, paranoid, angry, and even actually violent, savagely slamming the door of his house on Rena's fingers when she put her hand through the crack while attempting to convince him to let her in to make things up with him, while screaming hysterically at her to go away. So of course, they decide that the only sensible thing to do is to break into his house late at night while he's at home alone, forcibly hold him down, and scribble on his face with a marker to "cheer him up". They frankly had no right at all to be surprised when he snapped and brutally beat both of them to death with a metal baseball bat.
Himitsu no Akko-chan: Akko-chan in the aptly named '_____' episode asks her magic mirror to make her deaf and mute, thus, more empathic to the new deaf kid in her class. After realizing that she just wished herself mute, and her magic mirror could only obey to spoken commands, she spends the whole episode as a non-verbal deaf girl, moving from curiosity to deep-rooted depression. Keeping her rationality until the realization of her newfound handicaps kicks in, she then starts acting in a completely unreasonable way, ranging from acting as she were completely uncapable of any kind of communication to running blindly in a dangerous, isolated place, knowing that, being unable to cry for help, she'd risk falling in a ravine and being left there to starve. Exactly what happens to her. On the top of it, the deaf boy "inspiring" her wish sees into her self-destructive ideas and manages to save her from certain death.
Initial D: In Fourth Stage, Saitama's last racing team calls a bosozoku gang to beat up Project D after their loss. Unfortunately, they neglect the fact that the gang they hire is from the same region as Project D (thus likely to be fans) and that their leader was a former subordinate of Keisuke, the owner of the car they forced into a wreck during the practice runs (using a cheap trick of spilled oil). Needless to say, the current gang leader was NOT amused at being made to look bad.
Kikyo gloatingly tells Naraku EXACTLY why he can't kill her (Onigumo's heart is inside him). As a result he is able to rid himself of it and later use Onigumo's Heart to go ahead and kill her.
We also have this with Tekkei, who, despite being a powerful youkai (or, rather because of that), doesn't seem to learn her lessons well, as what had her sick in the first place was eating a poisonous youkai, however, she tries to eat Naraku and this gets her killed.
JoJo's Bizarre Adventure: Phantom Blood: After suffering numerous defeats at the hands of Jonathan Joestar, Dio Brando has been reduced to little more than a floating head. After getting the drop on him, his Dragon Wang-Chen gets irritable and rushes in to kill him, despite his master's warning not to underestimate him, even as he's dying, since Dio is living evidence of what Jonathan is capable of. Jonathan offs Wang-Chen in one shot.
In the Junji Ito Kyoufu Manga Collection story "The Hanging Balloons", the town is being haunted by a massive swarm of giant floating heads with nooses hanging from them, all of which are intent on killing everyone (especially the person with "their" face) and cannot be stopped. The protagonist's father... decides that, instead of locking the doors and windows and remaining safe, he needs to go to the office and get some paperwork done. When his children point out the very clear danger waiting for them outside, he says he can just protect his neck by wrapping his arm around it. Predictably, only a few steps out the door, he's snagged by a noose and dragged away.
Kagewani: Takeru, despite having his crew killed off mysteriously, decided to film a cryptid so that he can gain fame in being the first person in Japan to actually see it live. He didn't live that long since the cryptid snuck up on him and killed him.
High Admiral Fritz Josef Bittenfeld from Legend of the Galactic Heroessomehow manages to avert this trope, in spite of his Hot-BloodedHair-Trigger Temper, and as shown early on, being incredibly easy to bait into a trap. It's worth noting that some of his more questionable actions were a result of how aggressive he is, as opposed to him being legitimately dumbnote in fact, if he toned his aggression down, he'd probably be one of the smartest admirals in the series. Interestingly, this trope would have been played straight in regards to him, considering the type of series LOGH is, since the author did plan on killing him off eventually, but he somehow managed to survive.
Kirby: Right Back at Ya!: King Dedede is so focused on his grudge with Kirby, he continuously orders monsters from Nightmare Enterprises to get rid of him, even though some of those monsters end up nearly killing him, both on purpose and by accident. It’s only thanks to Kirby he doesn’t end up dead. In fact, he’s too stupid to realize that Nightmare Enterprises is just a front for galactic conquest and he’s just an Unwitting Pawn. At the end of the series, he mourns from the fact that he can no longer order any monsters, and this is after the company’s salesmen basically told him that he has outlived his usefulness to them prior to the final battle.
Mazinger Z: Several characters of the series (including The Hero or its TsundereBattle Couple) get at least one occasion where they seem determined to off themselves. The civilians thought it was a good idea remaining near from the place where a Humongous Mecha and a Robeast were fighting, or blamed the heroes for the destruction and deaths Hell and his lackeys were responsible of, or pressed the Government to yield EVERY TIME Dr. Hell was blackmailing it are good examples. A good, specific example is Yuri, Bratty Half-Pint Sayaka's cousin: Let's go over the facts, Yuri. You are Delicate and Sickly and can't run or move quickly because you need a wheelchair. You know there is a giant robot in the city, stomping on buildings and people. Kouji has gone out to stop it after telling you very clearly you must stay in home because you are safer. Still do you insist on leaving the home and go to where the giant robots are fighting because you have a crush on Kouji and you want to see him? Okay, you can leave. After all, what can possibly go wrong?
Mobile Suit Gundam: Unlike the other members of the Zabi family, Kycilia Zabi knows Char Aznable's true identity as the son of Zeon Deikun, a man believed by many to have been assassinated by her father Degwin. She also knows that Char was with her brother Garma when he died, yet never connects the dots that Char was responsible for Garma's death and reinstates his commission after her brother Dozle suspends him for incompetence in 'failing' to protect Garma. Predictably, inviting the viper that is Char to her breast ends with Kycilia getting her head blown off by a bazooka courtesy of everyone's favorite mask-wearing traitor.
Jamitov Hymen, the leader of the Titans, is for much of this series one of the most powerful men in the Earth Sphere. And yet, for all that political weight and savvy, he seems pathologically incapable of selecting even one loyal officer to surround himself with. He selects Bask Ohm, a psychotic General Ripper, to be his Dragon chooses habitual screw-up Jerid Messa to be his disciple, and recruits self-styled Dark Messiah Paptimus Scirocco from the Jupiter Energy Fleet to bolster the fighting power of the Titans. Not only do none of these three men have any loyalty to Jamitov (with the very thin exception of Jerid who defends him from assassination but still plans to succeed him one day), all of them are in fact conspiring against Jamitov, and the Zeta movies reveal that even if Scirocco hadn't killed Jamitov that Bask would have done the dirty deed.
Jamitov's treatment of Haman Karn is similarly hilariously suicidal. Haman is a highly dangerous and unpredictable warlord leading The Remnant of the group his organization was created in part to stop. When she seemingly stabs the Titans in the back during a major battle, he decides to meet with her to work things out. Minutes into the meeting, she announces that her side is on a mission to destroy his main base and then throws a poison gas capsule into the room that nearly kills him—said mission is successful. Astoundingly, after all this, Jamitov decides to attend a private meeting with Haman again—really, the only reason she didn't kill him in that meeting is that Scirocco does it first and blames it on her.
Adenauer Paraya, The Federation's point man in their negotiations with Big Bad Char, is the brain trust who decides that the best way to appease a terrorist currently conducting a campaign of dropping giant space rocks on Earth is to give him.... a giant space rock. One loaded with nukes, even, and he goes so far as to mention that the thing's engines are still fully functional. He is shocked, shocked!, when Char promptly betrays the agreement, and spends the rest of his onscreen time doing his best impression of the Persian messenger's Villainous Breakdown from 300 ("We had a treaty! This is madness!") until his daughter Quess blows him away.
Chan Agi, Amuro's Girl of the Week, is a Londo Bell technical officer whose job is to analyze the resident Plot Technology, not sortie in combat. Needless to say, she deploys in the final battle under the bizarre logic of "Amuro needs more psycoframes!" but instead of going to help Amuro she veers in on Quess and Hathaway because someone had to Shoot the Dog that Quess had become. While she does manage to shoot down the distracted Quess in her gigantic Alpha Azieru, an unstable and emotionally devastated Hathaway promptly shoots Chan herself.
Even Char himself is considered by many to be this, as he secretly forwarded his organization's superior technology to Anaheim, knowing Amuro would receive it and build a custom Mobile Suit for himself with it. Whether this self-defeating behavior was the result of a misguided Worthy Opponent view of his rival Amuro or a degeneration into outright Death Seeker is unknown, but what it not is rational. Naturally, this film marks his death, and it doesn't take a Mobile Suit genius to guess who offs him. Taking lessons from Vegeta, Char?
While she at least has the excuse of With Great Power Comes Great Insanity, the aforementioned Quess Paraya also richly qualifies. Despite being a 13-year-old girl with no combat training she eagerly leaps into an armed fight between Amuro and Char, allows herself to be subjected to the same Cyber-Newtype enhancement procedures that have driven multiple characters before her into insanity (among them resident Neo-Zeon Cyber-Newtype Gyunei Guss, who experiences steepSanity Slippage the moment Quess enters his orbit), and most extremely, launches herself out of her Mobile Suit's cockpit during battle while not wearing a spacesuit. Even Char himself is flabbergasted!
Mobile Suit Gundam: Iron-Blooded Orphans: Carta Issue had already met Tekkaden in battle, where they proved that they don't believe Talking Is a Free Action and attacked her while she was in the midst of a speech and disrupted her men's Attack Pattern Alpha mainly by ignoring it. She's sent to fight them again — and instead of simply destroying the train they're on, she stops them and tries to issue a formal challenge to a three-on-three duel of honor. To no one's surprise but her own, Mika attacks her before she's finished talking. When one of her men hangs around outside his cockpit yelling about the lack of honor, he's turned into a red smear in the snow as Mika proceeds to kill all three of them.
Adolf Junkers. First, he runs straight into traffic, then he sees a security guard fall down dead, leaves his room, and runs into an unlit area at night. When he knows someone really nasty is trying to kill him. Is anyone surprised when Junkers is found and shot to death?
Richard Braun, who's investigating a string of serial murders, more or less deduces that Johan's behind them all. Yet he doesn't think he should tell anyone when Johan shows up at his apartment and invites him out. Shortly after this, he follows Johan up to an abandoned rooftop (in the middle of the night) while shouting, "I know what you're up to, kid!" To no one's surprise but his own, it ends badly.
Joseph Greer fatally shoots Alyssa with Miyu nearby, but does not run away immediately afterward, instead announcing his reasons for doing so. Within moments, an enraged Miyu kills him.
During her confrontation with Shizuru, Haruka not only unnecessarily insults Natsuki, but continues to insult Shizuru even as her Element is drawn rather than stop provoking her or run away as Yukino suggests, thus forcing Yukino to try to defend her, leading to the destruction of Yukino's CHILD Diana, and Haruka's own death.
When Nao first encounters Shizuru while attacking Natsuki, she is easily defeated. In response, she kidnaps Natsuki again, this time for the express intention of luring Shizuru out. To make matters worse, by this time, Shizuru has gone insane from Natsuki's rejection, and not only destroys her CHILD Julia, but tries to finish off Nao before Natsuki intervenes.
Idiot Hero Monkey D. Luffy. He's a genius when it comes to fighting, and no fool when it comes to friendship, but this trope when it comes to almost anything else. Perhaps the most notable instance is in the Alabasta arc: Crocodile set a trap for them in his casino …by setting up a sign that directed VIPs to the left and pirates to the right. Luffy, who could not tell a convincing lie to save his life or anyone else's pre-Time Skip, goes right, and winds up in a Sea Prism Stone cage.
In Luffy's backstory, a mountain bandit, riding off the high of his own ego upon being issued a bounty of eight million Berry, decides to mock and belittle the pirate crew in the local bar. Apparently he wasn't in the habit of reading the news, because he failed to recognize Red-Haired Shanks, who, even if he wasn't recognized as one of the Four Pirate Emperors yet (i.e., the four people in the running for the title of World's Strongest Man), definitely already had a bounty measured in the billions. Shanks actually took it with grace, deeming the insult not worth getting upset over. But then the mountain bandit had the bright idea to threaten to kill Luffy. Shanks did deem that worth getting upset over.
While you might be able to get away with underestimating people you don't know if you live in one of the Blue Seas and are reasonably badass, the Grand Line is where the toughest of the tough converge. You might still be able to get away with it if you're someone visibly high on the totem pole, like a Warlord or an Emperor. But if you're just a low-level pirate captain, you should really shut up and show some respect to others, because you never know if they're stronger than you realize. Bellamy and his first mate Sarquiss got beaten up by Luffy when they made that mistake, but that isn't the suicidally stupid part. Bellamy had the good sense to learn his lesson after that. Sarquiss, however, never stopped casually disrespecting strangers and never feared there might be consequences...until he belittles and threatens Blackbeard.
Priest Gedatsu in Skypiea. He has to be reminded by one of his lackeys that he needs to open his mouth in order to speak, and it's a good bet he has on occasion forgotten to breathe and needed to be reminded of that too. After Chopper defeats him by punching him head-first into the Island Cloud below, Gedatsu ends up activating the Jet Dials on his feet in his struggle to escape, sending him through the clouds and all the way down to the world below.
When the Straw Hats are fighting the zombie giant Oars, Chopper examines Oars' body and concludes that the ancient giant died of the cold...because he was walking around a frozen climate in just a loin cloth around his waist. Hearing this, Zoro and Sanji exclaim that they don't want to lose to such an idiot.
Camie the Mermaid has a bad habit of being completely unaware of her surroundings at the worst possible time. As a result, she had accidentally been swallowed by around twenty Sea Kings, captured by slavers over thirty times, and run into who knows how much other trouble. The only reason she’s still alive is because every time, she gets rescued by her friend Hatchan.
Bluejam, a lowlife pirate, agrees to commit an act of mass murder in exchange for the King of Goa making him a noble. He actually expects the King to honor the deal, and doesn't see that he's being set up to take the fall for the massacre. He ends up burning to death in the fire he set.
The Fake Straw Hat Pirates. Notably, they picked fights with members of the actual Straw Hats despite being very weak (though to be fair, Usopp's wanted poster doesn't show his face,note but instead shows his alter ego, Sogeking both he and Nami had changed looks during the Time Skip, and Luffy was wearing a ridiculous Paper-Thin Disguise, so they hadn't recognized them) and tried to hunt them down after being casually defeated and mauled by them.
Their plan to take on the New World involved using Luffy's reputation to recruit an army of powerful pirates, then sending them out to take out any danger that the aforementioned reputation didn't scare away first. This might seem like kind of a clever plan at a casual glance, but the New World is loaded with pirates who still consider Luffy a rookie, and couldn't honestly care less about his accomplishments up to that point; not to mention there are numerous obstacles and dangers that are far too much for any pirate that was available on Saobody at the time, or simply require knowledge or skill rather than muscle to navigate. Not only that, but they also attracted the attention of pirates who were only joining so they could kill Luffy unawares in order to boost their own reputation. Sentomaru, sent by the Marines to arrest them because their informants had mistaken them for the real deal, actually called them morons for impersonating the Straw Hats after smacking around the fake Luffy. What added to their misfortune is that around the same time they started recruiting, the real ones were about to reunite and journey into the New World. Really, a combination of bad luck and stupidity ensured that the Fake Straw Hats were never going to make it out of Sabaody.
Hody Jones. Most of his plan was well thought-out and clever, and may very well have worked out as well as he hoped, were it not for one decision that he made that makes him fit this trope to a T: he deliberately provoked the Straw Hat Pirates. He knew of their reputation and everything that they had done, but he was too caught up in arrogance and fanatic racism to consider any human a threat to him. How does that turn out? He and his army of 100,000 are dropped onto the receiving end of a Curb-Stomp Battle against the nine Straw Hat Pirates and Jinbe.
Even worse, Hody wanted to attack the surface's population. Population filled with people like Kaido, Big Mom, Garp and the Admirals. This guy and his crew were lucky that the Straw Hats stopped them before they even get out of Fishman Island, or they're going to be massacred in seconds.
This was Sanji's reaction when he found out that Caesar Clown, for all his genius, swindled money from Big Mom. ThatBigMom. Small Name, Big Ego, indeed.
The World Nobles/Celestial Dragons. Extra credit goes to Saint Mjosgard and Donquixote Homing, who learned the hard way that the only reason people don't attack them is the threat of retribution from an Admiral. Mjosgard antagonized the Fishmen after finding himself trapped in their city, and would have been killed if not for Otohime's intervention; to his credit, he did end up becoming a better person later on. Homing's case is even worse: for all of his good intentions, his stupid decision to give up his status as a World Noble and live among those who despised said nobles, especially given that he picked a nation to move to that wasn't under the authority of the World Governmentnote If he picked a WG nation, the people might at least have let his family be out of fear of retribution, caused the ruin of his family and the death of his wife, got himself and his two young sons (one of them being a massive Creepy Child) subjected to Cold-Blooded Torture... and at the end his creepy son ended up killing him.
The anime makes Homing even worse. In the manga, he was at least smart enough to realize he shouldn't let anyone else know of his status as a former World Noble.note It's hinted that nobody would have found out for sure if Doflamingo hadn't acted as if he was still on Mariejois, lending credence to the suspicions of those who suspected the Donquixote family of being World Nobles. In the anime, he's stupid enough to tell others that he used to be a World Noble, and that was what led to everything going wrong.
And even those decisions weren’t the dumbest thing a World Noble ever did. The stupidest decision any World Noble ever made was when Saint Charlos tried to enslave Princess Shirahoshi at the Reverie. To clarify, he tried to enslave the princess of one of the World Government’s member nations in front of all of the member nations’ rulers. If Saint Mjosgard hadn’t stopped him, every last one of the member nations would have gone Revolutionary rather than risk the World Nobles doing something similar to them on a whim, and the World Government would have fallen. Mjosgard basically stopped Charlos from signing the World Government’s death warrant. And the other World Nobles don’t even realize this. All they saw was Mjosgard allowing one of them to be assaulted to protect someone they see as beneath them, and they execute him for his "crime".
In the anime-exclusive Warship Island arc, a mercenary named Eric the Whirlwind tries to take on the Straw Hats as the Going Merry begins to sail up Reverse Mountain. He reveals himself to them while standing on the railing on the edge of the ship. Nami simply knocks him off the ship and into the water. Eric the Whirlwind was a Devil Fruit user, meaning he couldn't swim, but as pointed out by Usopp, even if he could, it wouldn't have made a difference with the current going as fast as it was, thereby officially making Eric the first named character to die in the anime outside of a flashback.
In another anime-exclusive arc, a low-level pirate by the name of Bill decides to take a contract working for Gildo Tesoro, which means working in the New World. Bill and his men are woefully unprepared to fight New World-grade opponents, as demonstrated when they pick a fight with the Barto Club, and by extension the Straw Hat Pirates. The only reason Bill and his men didn't die was because the Straw Hats are leery about killing unless they have no other option; had they picked a fight with a different crew, such as the Kid Pirates or the Firetank Pirates, it would have been the end of them.
Hiroshi. He's prone to things like staying in a car with someone making creepy advances on him, walking around town at night after witnessing a brutal murder, specifically walking around the areas another classmate warned him to stay away from, seeing nothing suspicious in being called up at night or being asked to go into an abandoned barn...
Isuzu, for the most part, manages to make the right decisions to stay alive until Episode 11, wherein she sees the villain (whom we should add is highly unstable by this point in the story) walking through the forest. Instead of reporting it to the authorities, she decides it would be a better idea to follow them into the forest alone. While wearing bells tied to her wrist. This Ax-Crazy has a gun.
Overlord (2012): In order to further their plans, Nazarick props up a noble of the Re-Estize Kingdom, Philip Dayton L'Eyre Montserrat, to head his own faction of nobles within the kingdom. Philip is, to put it lightly, an idiot (one "brilliant" idea he had was to force his farmers to switch from grain to cash crops on the brink of a famine), and Nazarick intends for him to stir up trouble in the kingdom with his idiocy, preferably the kind that would lead to a civil war that would give the Sorcerer Kingdom pretext to invade and annex Re-Estize. What he actually ends up doing is raid a relief caravan the Sorcerer Kingdom was sending to another Kingdom, just so that he could resell the plundered grain. Literally everyone is scratching their heads at why Philip did something so monumentally stupid, to the point that everyone's first assumption is that he was manipulated, magically or otherwise, by some larger power, or that this is some sort of power play, when the reality is that Philip really is that stupid. As for Nazarick, while they do end up getting the pretext to invade that they wanted, it's far earlier than they ever planned for, and as a result they have to change track from conquering the kingdom, to razing it to the ground.
Parasyte: Kana Kimishima, a girl with the ability to sense the protagonist, Shinichi Izumi, via the Parasite that shares his body, which quickly leads to her becoming infatuated with him. However she cannot distinguish between him and other Parasites, which prey on humans. Shinichi repeatedly warns Kana that he is dangerous and that she shouldn't get mixed up with him. She not only ignores his warnings but also lies to him, claiming that she can tell him apart from other Parasites. Kana's obsession leads to her death when she senses the aura of a Parasite. Convincing herself that it must be Shinichi, she follows the signal to an abandoned building, only to find another Parasite gorging on a fresh corpse. Shinichi does arrive but not in time to save her.
Giovanni in the same movie, actually. He told Mewtwo that he was "created by humans to obey humans" and, when Mewtwo began blowing up his entire laboratory, what does he do? Shout, "Stop this now!" Yeah, that's always worked in the past. Lucky for him he had Plot Armor...
Ranma ½: Many, if not all, of the characters get at least one occasion where they act like this. However, this trope gets played to its actual conclusion in one late-manga story, which really makes it into Mood Whiplash. One character's father receives a scroll detailing a martial arts style which makes use of a lot of brute-force tricks, and a bearhug attack explicitly stated to be capable of snapping a man in half. Kumon Senior intends to use these moves to revitalize his dojo, which is dilapidated to the point it's being held aloft only by a single, rotting pillar, but he decides to master this spine-shattering bearhug by practicing on the pillar. Naturally, when he succeeds in learning it, the whole house collapses on top of him, killing him.
Rave Master: Main character Haru Glory's mother Sakura. When someone is telling your husband about how they're going to make him suffer by being alone, you don't run up to them and let them impale you.
In the "New Generation" episodes we're told of a town that tried to fight off the Invid invasion with sticks, pitchforks and axes. The Invid always go around in mechas, the smallest and weaker being the 2.3 meters-tall Invid Soldier that is still invulnerable to normal small arms fire. The town survived, but only because the Invid (that showed up with a squadron of slighty taller but MUCH broader and stronger Scouts) apparently decided they were too dumb to pose a danger.
Requiem from the Darkness: The main character Yamaoka Momosuke. He has a habit of blindly trusting and attaching himself to even Obviously Evil people, trying to sacrifice himself for others and jumping in to save people from sword-wielding maniacs without any other means to defend himself than yelling "Please calm down!" He'd probably have died at least once every episode if it wasn't for Mataichi's team always saving his ass.
Rozen Maiden: Kanaria has some shades of this during the series, but it becomes blatant obvious during the final battle of the second season: not only she is the cause of turning Suiseiseki's Heroic Sacrifice in a Senseless Sacrifice by going back to the battle field, she also is killed by Barasuishou after the strings of her violin snaps and she forgets that, since she has Suiseiseki's Roza Mystica, she could use her Green Thumb powers.
Ryu's Path: Discussed. Ryu derides the ape/human beasts as this trope and says they are a burden to carry. Hearing this, the apes resolve to help Ryu and do better.
The Saga of Tanya the Evil has the entire military of The Duchy of Dacia, who not only marched three divisions of infantry into a highly industrialized military super power with access to flying magical troops, using outdated military formation without any artillery, air support, or mages of their own to support their infantry, but also don't even try to hide their troop movements or radio transmissions. And just to add some more idiocy to the mix, not only left their capital poorly defended, but were already celebrating their "victory" before the first battle. It goes without saying, that they almost immediately receive a brutal Curb-Stomp Battle, when Major Tanya Degurechaff's battalion of only forty eight mages route their army of fifty thousand infantry, capture their commanding officer, and just for good measure, stroll into their capital without any resistance and blow up their munitions plant, pretty much defeating the entire country in one night.
Sailor Moon: Because Usagi/Serena is such a klutz (as well as a crybaby), the other Sailor Senshi/Soldiers/Scouts, and the two cats started pegging her as this (or at least that's what DiC's English version would like us to think...). However, this applies more to the first anime than to the manga (especially the crybaby part).
Saiyuki: Koukaji in the anime version of the first series. He had previously been beaten with an inch of his life by Son Goku with his power limiter removed, and in the finale, he decides to try and fight him on his own again, and nearly gets killed, again. This wasn't in the manga.
The Secret Garden: Lilias Craven got the bright idea to climb, a tree, while pregnant, to grab a flower Camila called pretty. Even though Camila yelled at her to stop, she kept on climbing, and fell to her death.
Slayers: Princess Amelia, and to a lesser extent, Naga the Serpent. The latter is boastful and arrogant to the point that she ignores the reality of the situation around her (leaving Lina to do away with whatever situation they're in), while the former's view of morality is so black and white that she winds up in dangerous situations; anything that turns gray leaves her dumbfounded. While Naga's intelligence varies, Amelia's is more a case of flanderization that spread to other adaptations — she certainly wasn't this trope in the light novels that the series originated from, and in the anime, at least, she grows out of this trope over time. It also doesn't help for Amelia that she's a bit weaker than her companions; while Gourry The Ditz swordsman can fall under this, he generally doesn't because he knows more than he lets on and is more skillful than any other swordsmen in the series.
Princess Sya from Sleepy Princess in the Demon Castle doesn't have much in the way of common sense, and has died a few times because her need for a comfy sleeping spot outweighed her sense of self-preservation. At one point, she even purposely killed herself so she could take one of the Demon Cleric's coffins to use as a bed.
The members of Guild Moonlit Black Cats never bothered to ask why their newcomer, Kirito, is a lot stronger than them despite being at the same levels (Kirito actually has twice amount of levels compared to the gang, but deliberately hides it; Sachi finds out but doesn't tell anyone). Instead they believe themselves to be strong enough to tackle an over-leveled dungeon head on. They get themselves locked in an obvious trap room with one treasure chest, where they easily get wiped out by a Zerg Rush.
A squad of the Army's men decides to attack the boss of the 74th floor despite having only a group of 10 people who aren't in good enough shape to even attempt such a thing. Their leader pays for his mistake with his life, and only Kirito's intervention (along with unveiling his Dual Blades skill) prevented the rest of the squad from being wiped out.
While Gun Gale Online isn't a deadly game the same way SAO is, one guy named Jack gets his character killed, and thus eliminated from the tournament, simply because he yelled out to his teammates rather than checking his status. An enemy then discovers his position and pretends to be one of Jack's teammates long enough to kill him. The attacker only lives long enough to gloat about it before getting gunned down by an enemy he hadn't noticed.
Like the Bullet of Bullets tournament in the parent series, Squad Jam is largely a game of stealth, requiring its participants to move strategically and find the enemy before they get noticed themselves. As such, Team ZEMAL, an entire team of machine gun enthusiasts whose strategy entirely consists of More Dakka gets eliminated fairly quickly and unceremoniously by more competent players.
Team RGB, or Ray Gun Boys, makes Team ZEMAL seem competent (especially since they debut in Squad Jam 3, around the time Team ZEMAL Took a Level in Badass), by virtue of taking energy weapons to Squad Jam 3. For those who don't know, energy weapons don't require ammo and aren't affected by the wind, but players have shields designed to protect against them, so they're purely for PvE battles, rather than a PvP tournament like Squad Jam. Team RGB runs into Team SHINC, which placed second in Squad Jam 1 and fourth in Squad Jam 2, and the "Amazons" quick work of Team RGB.
Taboo-Tattoo: This happens to Touko in Episode 8. While being escorted to safety by Tom, she runs off, refusing to leave Seigi. After Seigi consumes BB, Touko is later devoured by Iltutmish the minute she finds Seigi.
Tengen Toppa Gurren Lagann: The Red Shirts from the battle against Teppelin. Our leader has just obliterated himself against the mysterious shield surrounding our enemy's city? Quickly! More of us must ram into it so that his death will not be in vain!
Tytania: Duke Idris Tytania betrays another member of the clan he was sent to rescue, and stands by to watch while the enemy destroys his ship, presumably killing everyone on board, including Idris's subordinate, Berthier, who thought he was in on Idris's plans. Berthier actually manages to get to an escape pod and survives, though he is permanently crippled. Then, although he is presumed dead and could easily just take off, he goes back to continue serving the guy that just double-crossed and tried to kill him. Yeah.
Yu-Gi-Oh!: Jounouchi/Joey's first Duel with Kaiba is like this. Sure, when you're up against a powerful monster and don't have something to beat it, the smart thing to do is keep throwing monsters out as meat shields until you get something that works. The problem is that Jounouchi plays all of them in Attack Position, meaning that every one Kaiba destroys chips away at his Life Points, so that when he finally plays one the few cards in his Deck that can stand up to Kaiba's Rabid Horseman, he's in prime position to lose as soon as Kaiba plays his signature Blue-Eyes White Dragon. Nothing was at stake with that Duel, thankfully.
In Yu-Gi-Oh! The Dark Side of Dimensions's prequel manga, Seto is so focused on seeing and dueling Atem that he listens to Sera and tries to break into the afterlife using nothing but his own brainwaves and without any sort of protection. It would have killed him if Mokuba hadn't intervened.
Idiot Protagonist Jaden/Judai nearly dooms the world by handing over the key to a Kill Sat, then expecting that Season's Big Bad, Sartorius/Saiou, to not activate it until after defeating Judai in a Duel first. The fact that said Big Bad didn't attempt to duel him first was a shock to many fans, as Saiou was the probably the first smart villain in Yu-Gi-Oh! Though to be fair, Saiou did have Edo/Aster in a deathtrap over a pit of lava and was threatening to kill him if Judai didn't give him the key, so Judai didn't have much choice.
Also, Saiou made a bit of a dumb move with that himself. The deathtrap was a scale, and to save Edo, Judai had to throw the key on the other side of the balance. It sounded like a good idea, but when Saiou actually went to get the key, Neos was able to block his path, which gave Kenzan time to pull Edo out of the way, which forced Saiou to Duel Judai. So, maybe Judai was dumb, but Saiou wasn't all-too smart either.
Divine needs a mention here: after being tricked into an Engineered Public Confession that he killed Misty's brother, not Aki, Misty turns on him in her anger. Divine's reaction? Taunting her about how her brother was too weak to survive his experiments. This despite knowing full well Misty is a Dark Signer, and knowing from firsthand experience that Dark Signers have supernatural powers far stronger than his own. Most egregiously of all, her Earthbound God Ccarayhua, a lizard nearly the size of a skyscraper, is standing right next to her. Divine is subsequently Eaten Alive.
Another good example in the franchise was Yliaster member Kodo Kinomiya. Assigned by Godwin to test whether or not Aki was a Signer or not during the Fortune Cup, he knew that Aki had powerful Psychic Powers, was able to literally warp reality during a duel and had very little control over her powers when enraged. Yet, he deliberately tried to make her angry during the duel by insulting her repeatedly. In fact, the original version, as opposed to the dub, doesn't even make clear whether or not he survives Aki's final attack. (Well, maybe you could blame it more on his greed than his stupidity. He had initially demanded five times his usual salary for doing it; eventually, he realized that it wasn't worth losing his life over, and tried to end the duel quickly, but by then, it was too late.) He also deliberately uses a strategy that relies on refilling his own Life Points after he takes damage. It's not that the strategy itself is bad (it actually keeps him in the duel for a very long time), but the fact he chose to deploy it against someone who makes all damage they inflict in the duel real is what makes it this trope. He basically ends up being tortured because while his Life Points were healing, his actual wounds weren't.
