[-[[caption-width-right:223:[[ThisIsGonnaSuck Well... That's gonna leave a mark.]]]]-]
->''"'''Maxim #37:''' There is no "overkill". There is only "open fire" and "I need to reload."''
-->-- ''Webcomic/SchlockMercenary'', "The Seventy Maxims of Maximally Effective Mercenaries"
There are some opponents you want to defeat. There are some opponents you want to kill. Then there are the opponents whom you're not satisfied with until you've stabbed them, shot them, blown them up, unleashed the hounds on them, electrocuted them, irradiated them, jumped up and down on them, and then shot the remains into space on a rocket full of time bombs.
This trope comes in three categories (with some overlap): the killer either [[ComedicSociopathy loves violence for its own sake,]] or [[ThePowerOfHate wishes to express dislike for the target,]] or is GenreSavvy enough (usually due to fighting TheJuggernaut or an ImplacableMan) to know that ItsTheOnlyWayToBeSure. There Is No Kill Like Overkill may be played for comedy or for drama. If the former, another character may [[LampshadeHanging remark]] [[CaptainObvious "I think he's dead already"]] near the end of the process.
May be employed successfully: see NoOneCouldSurviveThat. Unfortunately often leads to NeverFoundTheBody, thus setting up OnlyMostlyDead or UnexplainedRecovery. JokerImmunity means even overkill is useless, but even ''that'' is better than a NoSell.
Much, much more common in fiction (especially of the 'revenge fantasy' type) than in RealLife violence. To a strategist, overkill is AwesomeButImpractical because the ''risk'' of enemy survival is vastly outweighed by the ''certainty'' that you're spending a fortune in time, material and (usually) manpower to ensure the enemy's death. The weaker and less numerous the target, the more wasteful overkill is.
For common forms of overkill, see MultiDirectionalBarrage, BeamSpam, MoreDakka, MultipleGunshotDeath, and/or MacrossMissileMassacre. For situations in which the overkill destroys the whole point of the combat, see PyrrhicVictory. Compare ChunkySalsaRule, RasputinianDeath, CriticalExistenceFailure, VideogameCrueltyPotential, SurplusDamageBonus, DisproportionateRetribution, and DeaderThanDead: contrast CherryTapping and OnceIsNotEnough. Characters who don't have enough overkill at their disposal just might resort to crossing the GodzillaThreshold instead.