->''"Friendly fire, isn't."''
-->-- '''Murphy's Law of Combat Operations'''

Combat or other dangerous elements in a setting or plot conflict increase the drama by exponentially increasing the danger to the characters. But sometimes that danger comes from an unexpected angle. You look up to see who is on the other end of the knife you've just been stabbed with... and it's ''your best friend''!?! This sort of thing can occur by accident, by treachery, or, perhaps most tragically, because they had to.

In RealLife, friendly fire usually occurs as a case of mistaken identity: innocent civilians, allies, or neutral forces, are mistaken for enemy forces and fired upon, or else the attacker simply didn't know the friendly unit was in the line of fire. While it might be hard enough to imagine the horror of killing someone you like accidentally, in fiction, to play the drama up even more, the attacker often is all too aware of what they are doing.

Given the tropes themselves tend to be fairly broad, there may be some overlap in a given situation depending on the perspective. For instance, even if the person pulling the trigger makes a genuine mistake, they might have been manipulated into doing so by a third party deliberately seeking to cause harm.

Note: Please place non - {{trope}} examples in the subtropes listed rather than listing them here.

There are many forms of Friendly Fire, from nastiest to least nasty:

!!Category A: Deliberately, out of a callous disregard for life (note: doing any of these invariably marks you as a {{villain}} or AntiHero):
* BadBoss: mistreats his own minions for trivial reasons.
* DisposableIntern: The intern is so unimportant killing them doesn't matter.
* KickTheDog: commit an unnecessary evil act to show the audience you're not nice.
* WeHaveReserves: callously place minions in a situation where they will be slaughtered, as part of a strategy.

!!Category B: Deliberately, out of treachery:
* CavalryBetrayal: TheCavalry that you've been praying for isn't really on your side.
* TheDogBitesBack: A minion takes his revenge after being the subject of too many KickTheDog moments.
* ForcedFriendlyFire: A character gains control of their opponent's firearm and forces them to shoot it at allies
* PleaseShootTheMessenger: A letter instructs the recipient to kill the man who delivered it. The sender, the messenger, and the recipient are supposedly on the same side.
* ShootTheDangerousMinion: A villain offs his henchman out of fear that the henchman will betray him.
* TheStarscream: A mook who serves the BigBad but intends to overthrow him.
* UnfriendlyFire: A murder disguised as a combat death ({{Fragging}}, see also {{Team Killer}}).
* UriahGambit: A BadBoss attempts to get an underling killed by proxy by sending them on a SuicideMission or any situation where their death will [[MakeItLookLikeAnAccident appear accidental]].

!!Category C: Deliberately, due to being faced with a choice between evils:

* DyingAsYourself: The way to cure a victim of TheCorruption is to mortally wound them, resulting in an ObiWanMoment.
* KillUsBoth: To stop an enemy for good, you've got to ask your friends to do this.
* MercyKill: To kill someone quickly who would otherwise face a painful or ignoble death.
** ICannotSelfTerminate: Someone wants to die, but doesn't have the means to off themselves, so the hero has to do it for them.
* SadisticChoice: A villain gives a hero a choice between letting one of two people die.
* ShootTheDog: To prevent a more innocent or pure hero from having to kill someone, another hero does it.
* ShootTheHostage: To stop an enemy, one must risk harming a hostage used as a HumanShield.
* TrialByFriendlyFire: Someone must act quickly to stop a threat and the solution requires putting your allies in the line of fire.

!!Category D: Due to an error in judgement
* FriendOrFoe: Mistaking an ally for an enemy. This is TruthInTelevision on the battlefield.
* HesAFriend: Mutual allies of the Hero come to blows before realizing their relationship, forcing the Hero to make them both back down.
* KickTheMoralityPet: Go too far and hurt an ally, prompting a HeelRealization.
* LetsYouAndHimFight: The author decides to set up a situation in a crossover to make the heroes battle each other.
* MyGodWhatHaveIDone: A realization that good intentions have caused great harm.
* SelfOffense: A character attacks an unknown potential assailant out of fear, anxiety, or paranoia, then discovers they've hurt an ally by mistake.

!!Category E: Completely unintentional
* CartwrightCurse: A character's love interests have a high mortality rate, through no fault of their own.
* FriendlyTarget: By choosing to face an enemy, a character places his friends in danger.
* IJustShotMarvinInTheFace: Mishandling a weapon and forgetting about gun safety.
* StrayShotsStrikeNothing: Although the trope itself is about missed shots being insignificant, notable aversions (the only examples listed) often involve the consequences of firing blindly and causing collateral damage.