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[[quoteright:259:[[ComicBook/PlasticMan http://static.tvtropes.org/pmwiki/pub/images/bear_trap1_4.jpg]]]]
[[caption-width-right:259:That's some mild language for what you just saw.]]

->''"I am justly killed with mine own treachery."''
-->-- '''Laertes''', ''Theatre/{{Hamlet}}''
%% One page quote is sufficient. For additional entries, please use the quotes tab.

The villain's own weapon or malicious plan is the cause of their downfall and/or death. This could be something as big as a MadScientist who creates monsters and/or a WeaponOfMassDestruction getting killed by their own creation, or as small as a prankster accidentally setting off their own trap.

In media intended for young children, it is often a DeathByIrony that releases the hero from the unpleasantness of actually killing their enemy; a more specific type of SelfDisposingVillain.

If the {{hero}} is not responsible for the death in any way, it can also be a KarmicDeath.

A "petard" is an explosive device (basically a bucket full of gunpowder) intended to demolish gates and fortified walls; being too close to the detonating explosive could well toss the engineers who planted it into the air. Thus, this term literally means "Blown into the air by one's own bomb" and [[JustForFun/TheZerothLawOfTropeExamples was first coined]] by Creator/WilliamShakespeare in ''Theatre/{{Hamlet}}'', though [[BeamMeUpScotty the original quote was]] "hoist ''with'' his own petard".

If an evil EldritchAbomination, GodOfEvil or otherwise supernatural evil entity gets [[DidYouJustPunchOutCthulhu Punched Out]] by the same powers it gave, you have a FaustianRebellion in action. If it's an AncientConspiracy, GovernmentConspiracy or other organisation whose AppliedPhlebotinum is empowering the one who will bring them down, you have a PhlebotinumRebel. If it's done by making him hit himself, it's StopHittingYourself. If it's a {{Mook}}, long abused, who finally snaps and turns against him at the last moment, it's TheDogBitesBack. If it's a VideoGame boss whose attacks can be redirected back at them ([[PlayingTennisWithTheBoss tennis-style]] or otherwise), it's TacticalSuicideBoss. GoneHorriblyRight is a sub-trope where a SuperPrototype works too well, destroying the person or persons who created it and/or threatening the world/galaxy/universe. If it's a vehicle that you just stole, it's VehicularTurnabout.

Can be the result of DidntThinkThisThrough, but not necessarily. Compare NiceJobFixingItVillain, ATasteOfTheirOwnMedicine, and BeatThemAtTheirOwnGame. The StreisandEffect is a subtrope of this, when the petard is censorship.

'''As this is often a DeathTrope, all Spoilers will be unmarked ahead. Beware.'''

!!Examples subpages:

* HoistByHisOwnPetard/{{Advertising}}
* HoistByHisOwnPetard/AnimeAndManga
* HoistByHisOwnPetard/ComicBooks
* HoistByHisOwnPetard/ComicStrips
* HoistByHisOwnPetard/EasternAnimation
* HoistByHisOwnPetard/FairyTales
* HoistByHisOwnPetard/FanFiction
* HoistByHisOwnPetard/{{Film}}
* HoistByHisOwnPetard/{{Literature}}
* HoistByHisOwnPetard/LiveActionTV
* HoistByHisOwnPetard/{{Music}}
* HoistByHisOwnPetard/MythologyAndReligion
* HoistByHisOwnPetard/{{Pinball}}
* HoistByHisOwnPetard/ProfessionalWrestling
* HoistByHisOwnPetard/{{Radio}}
* HoistByHisOwnPetard/TabletopGames
* HoistByHisOwnPetard/{{Theatre}}
* HoistByHisOwnPetard/{{Toys}}
* HoistByHisOwnPetard/VideoGames
* HoistByHisOwnPetard/VisualNovels
* HoistByHisOwnPetard/WebComics
* HoistByHisOwnPetard/WebOriginal
* HoistByHisOwnPetard/WesternAnimation
* HoistByHisOwnPetard/RealLife