An extreme version of WouldntHitAGirl that extends to actually killing people.

For some reason an otherwise very good fighter can't kill or harm certain people -- usually due to a FreudianExcuse, a curse, or some other prohibition -- and this is almost always a gateway for this [[AchillesHeel weakness]] to be [[FlawExploitation used against them]]. If this fact is introduced early on, it's usually a ChekhovsGun and will almost certainly be used sometime in the story.

Generally, if the person affected by SelectiveSlaughter is a villain the FlawExploitation is treated as ingenious on the part of the heroes, but if the person is TheHero, it's considered low. Yeah, a bit of a DoubleStandard. This very often results in a GoThroughMe scenario.

See also NeverHurtAnInnocent, WouldntHurtAChild, KickThemWhileTheyAreDown.
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!!Examples:

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[[folder:Anime and Manga]]
* After fully awakening her SuperPoweredEvilSide, Priscilla in ''{{Claymore}}'' literally walks right by the young Clare after killing the other Claymores, and it's explained that whenever she attacks a place the young girls are spared, as if she doesn't even see them. The regular Claymores are also prohibited from killing humans, though as Teresa explains, this is voluntary on their part, and that despite the consequences they can and sometimes do break it.
* Enishi in ''Manga/RurouniKenshin'' is unable to harm young women and becomes violently ill if he tries due to what happened to his sister (and he was witness to) and this becomes a crucial plot point twice: [[spoiler:He didn't really kill Kaoru, he just abducted her and left a very realistic dummy to serve as a body, and in the final fight with Kenshin Kaoru throws herself between them and stops him before he kills Kenshin]].
* The Peacemakers from ''ScrappedPrincess'' can kill everyone except for Pacifica, the person they have to kill, because [[spoiler:she was genetically engineered to be as much like their original master as possible]].
* A slight variation: Kurogane in ''TsubasaReservoirChronicle'' is put under a curse by Princess Tomoyo that will weaken him a little bit more whenever he kills someone. The idea is that it will teach him the value of life, as he lacked that as Tomoyo's personal {{ninja}}, but he sees it more as an inconvenience for most of the story. [[spoiler:It's later revealed that it wasn't actually a curse at all, but a protective spell, and she just lied about that in order to keep him out of trouble]].
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[[folder:Film]]
* In ''Film/RoboCop2'', the title character is prohibited from shooting children. The child criminal villain takes advantage of this restriction to shoot him.
** And previously, in the first movie, he was prohibited from harming employees of the company that made him.
* The Predator, in [[Film/{{Predator 2}} the second movie]], attacks a subway train full of people and kills only those who were armed [[spoiler: except for the policewoman, whom was spared because [[InfraredXrayCamera he could see]] that she was pregnant.]]
* Subverted in ''Film/DemolitionMan''. Wesley Snipes' character, Simon Phoenix, is prevented from causing any harm to Raymond Cocteau due to subliminal programming instilled in him while he was in suspended animation, soooo ...
-->[Simon points gun at Cocteau's head but cannot pull the trigger]
-->'''Simon:''' "Now that I have an army, I don't need you anymore! Never liked you anyway.. like an evil Mr. Rogers."
-->'''Cocteau:''' "Yes, you do! The programming prevents your harming me."
-->'''Simon:''' [[spoiler: [hands gun to other guy] "Will you please kill him? He's pissing me off."]]
* In ''Film/DjangoUnchained'', Django is mad enough to kill every white person in and around Candyland, making a special detour just to off the white mastiff handlers who train large dogs to rip black people limb from limb. However, during the final showdown, he takes care to courteously ask the negroes present to step to one side out of the line of fire. Apart from the one who actually ''has'' benefited from being a slave, Candy's Uncle Tom estate manager Stephen, who he saves for last.
* Professional [[ProfessionalKiller "cleaner"]] Léon in ''Film/TheProfessional'' has a strict "no women, no kids" rule when carrying out his jobs. This is part of the reason he helps Mathilda seek revenge against the drug dealers; they slaughtered her whole family, including her little brother.
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[[folder:Literature]]
* The Philosopher in Ian Banks' ''Literature/{{Transition}},'' a torturer, refuses to hurt women or children. He [[LampshadeHanging notes]] that some would claim that it was because he once heard his father raping his mother, but he believes that it's because he's a gentleman.
* In MercedesLackey's ''[[Literature/HeraldsOfValdemar Oathbound]]'' series, the sword Need has a ''geas'' that prohibits the wielder from harming women, and at least one villain has used a GenderBender to get around this.
* Patrick Bateman from AmericanPsycho seems to be unable to kill people who love him. He wants to kill his coworker, Luis Carruthers, but when he learns that Luis is in love with him, he's physically unable to do it.
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[[folder:Live Action TV]]
* In ''Series/BuffyTheVampireSlayer'', Spike is implanted with a device that causes him agonizing pain if he attempts to inflict harm on humans. Demons, on the other hand...
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[[folder:TabletopGames]]
* Averted in Warhammer40K: The Chaos god [[WarGod Khorne]] ''used'' to be the god of martial honor and prowess, whose [[BloodKnight followers]] would not attack defenseless victims. Nowadays, "Khorne cares not from where the blood flows, so long as it flows", and the only distinction is that they'll leave defenseless targets alone only as long as there's a WorthyOpponent nearby.
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[[folder:Theater]]
* The titular pirates in the Creator/GilbertAndSullivan operetta ''Theatre/ThePiratesOfPenzance'' won't attack orphans (as they are all orphans themselves), which leads to FlawExploitation from everyone they capture.
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[[folder:Web Comics]]
* In ''Webcomic/GirlGenius'', Von Pinn (basically a monstrous semi-robotic babysitter) chases after Agatha, but one of the students gets in her way. Said student is quite aware of the fact that Von Pinn is completely incapable of hurting her due to programming. When the PsychoForHire steps in and kills the student for her, Von Pinn gets mad and tries to kill her.
* In ''Webcomic/TheOrderOfTheStick'', [[spoiler: since a "Mark of Justice" was put upon him, Belkar cannot deal lethal damage to any living creature inside the boundaries of any city, town or village without setting off the mark -- thus restricting him to killing things outside the boundaries, destroying undead, or knocking people around with Nonlethal damage. And he still trips it off.]]
* Used after a fashion with Oasis in ''Webcomic/SluggyFreelance''. Her [[BrainWashed brainwashing]] causes her to automatically attack anyone she recognizes as a Hereti Corp employee. Several Hereti Corp agents get around this simply by saying "[[ISurrenderSuckers I quit]]." She ''can'' still kill them, but unless they do something do piss her off she has no reason to. The only person she's truly incapable of killing is Torg.
* Jack Noir, one of the villains in {{Homestuck}}, is unable to attack Jade after [[spoiler: Bec was prototyped, as Jack gained Bec's affection for Jade along with his power.]] This is used by Dave during a fight.
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[[folder:Western Animation]]
* Brock Sampson of ''WesternAnimation/TheVentureBrothers'' cannot kill women or children. He's not above killing anything else under the sky with gusto, and he'll even maim women (considering he plucked out his lover's eye), but his mentor taught him not to kill women or children as it's basically the [[MoralDissonance only moral high ground they can actually claim over their enemies]]. They're also probably just not covered by his license to kill (even though the undead apparently are).
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[[folder:Real Life]]
* Traditionally the Japanese ghost known as [[StringyHairedGhostGirl the onryo]] will attack everyone around it ''except'' the man who wronged it in life. This doesn't mean the man gets away unharmed, however, as usually the onryo is targeting the people close to him, and eventually the survivors will figure out who the onryo is going after...
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