Conveniently-Timed Attack From Behind

You've Seen It a Million Times. The hero is cornered. His back is to the wall, his gun is out of ammo, he's bleeding from at least one wound, and the bad guy has him dead to rights. Perhaps the hero is hanging from a ledge by his fingertips with a bad-guy standing over him, and the bad guy is about to play a round of "stomp the fingers." Whatever the case, things look bad for the hero.

But just before the mook can end both the hero and the franchise, one of the hero's allies shoots the mook from behind (or runs him through with a sword, or hits him over the head with something heavy) and thus takes out the mook. Regardless of means, someone has just come to the hero's rescue.

Often involves Version A of Bait and Switch Gunshot, or in some cases Impaled With Extreme Prejudice. A variation on Big Damn Heroes. compare The Cavalry

Anime and Manga
"Jacuzzi: Please, I don't want to kill you!
 * In one of the few real fight scenes in Higurashi no Naku Koro Ni Kai which isn't just a Curb Stomp Battle, one of the girls is cornered by a bad guy, and then Keiichi hits him from behind. Of course,
 * Vegeta saves Gohan and Krillin in this manner in their fight against Guldo. Despite being significantly stronger than him, the two Earthlings find themselves trapped by Guldo's time-stoppage abilities, and he is about to finish them off when Vegeta jumps in and slices Guldo's head clean off.
 * He also saves Goku in this manner when the good guys are fighting Android #19 in Dragonball Z
 * He does it again at the climax of the battle with Perfect Cell, allowing Gohan to turn the tide in their Beam-O-War struggle.
 * In fact, for a guy that spends half of the time banging on about his noble blood, and the importance of pride and honour in battle, Vegeta sure does like to fight dirty.
 * The Council likes to do this to the heros in Fairy Tail. They make a point of showing up right after the villain has been defeated, twice. One time just to question the guild, another to issue a life sentence to two people who just helped save the day.
 * In Baccano, when the anachronic storyline finally gets around to showing us some context on Jacuzzi Splot it's to see him in an alley, reasonably enough but a little overeffusively cowering and weeping in front of three guys with guns, begging them to put the guns down. They're rather puzzled because they were expecting a Badass. Then it gets weird.

Mook: Huh? Isn't it, you don't want to be killed by us?

Jacuzzi: No...I don't want you to be killed! So please...Donny...I'm sure they're going to put the guns down now...there's no need..."


 * And then a giant crushes one of them and an Action Girl cuts their throats, from behind. Jacuzzi has pals.

Comic Books

 * There were a lot of times early in Fantastic Four when some villain had three members of the group at gunpoint or otherwise at his mercy, but got attacked from behind by the Invisible Woman before he could fire.

Fanfic

 * In The Tainted Grimoire, during the climax of the St. Galleria arc, Auggie is saved from three members of the  like this.

Film
"Darth Vader: I have you now.
 * During the fight on top of the space drill in Star Trek, Kirk is hanging off the edge with a Romulan standing over him, trying to stomp on Kirk's fingers. Sulu comes to the rescue by running the Romulan through with his sword.
 * An extreme example occurs in the Judge Dredd movie, where this trope occurs not once, but twice in the same scene. During the confrontation with the desert cannibals. Toward the end of the fight, Dredd is about to be speared by the patriarch of the cannibal clan, when the bad guy is killed by a shot from the "cleanup team" sent to make sure that Dredd didn't survive. After the ensuing shoot-out, Dredd is again cornered only to have his attacker shotgunned by Judge Fargo, Dredd's mentor. Fargo is then literally skewered seconds later after saying hello by the cyborg cannibal.
 * And at the climax of that same movie, Dredd is hanging by his fingertips, with the recently-deceased Big Bad's mad scientist henchman standing over him with a gun, gloating about shooting him. Cue the Bait and Switch Gunshot as Judge Hershey, Dredd's partner, shoots the scientist from behind, saving his life. Using this trope three times in one movie may well qualify for some sort of record.
 * Happens at the end of Men in Black. After they think that Edgar is dead and are relaxing for a moment, he lurks in the background and then leaps up to kill them. Before anyone can react, L shoots him.
 * Marion Ravenwood knocks out a mook from behind with a burning log during the barfight near the beginning of Raiders of the Lost Ark just as he's about to shoot Indiana Jones.
 * She does this sort of thing again later during the fight on and around the Nazi plane. A German pilot is about to shoot Indy when he's hit over the back of the head, and we see Marion Ravenwood lifting some airplane wheel chocks triumphantly.
 * From Star Wars:

(One of Vader's wing-men explodes.)

Darth Vader: What?!

( Shot of Millennium Falcon coming out of sun.)

Han Solo: Ya-hew!

Tie Fighter Pilot: Look out! (Tries to turn but crashes into Vader's ship sending Vader spinning out of control and killing him).

Han Solo: You're all clear, kid. Now let's blow this thing and go home!"

"Orc: I'm gonna bleed you like a stuck pig!
 * Multiple times in The Lord of the Rings:
 * In The Fellowship of the Ring, Lurtz (the Uruk-Hai captain) is about to finish off Boromir when Aragorn appears to fight him off.
 * The Two Towers has a similar scene twice. After Merry and Pippin are captured, one of the orcs is about to kill a helpless Pippin, when he's suddenly stabbed from behind by a Rider of Rohan. A short time later, the same orc has Merry at his mercy ... and is promptly stepped on from behind by Treebeard.
 * The Return of the King features a scene where it seems Frodo (captured, naked, bound, weaponless, and Ringless) is about to be killed by an Orc:

[Orc gets run through with Sting, wielded by Sam]

Sam: Not if I stick you first."


 * Trinity, in The Matrix: - "Dodge This."
 * In The Simpsons Movie, Russ Cargill is about to shoot Homer when a boulder falls on his head and knocks him out, courtesy of little Maggie.
 * Done in Blade Runner when Deckard has lost his Hand Cannon, Leon picks him up and says, "Time to die..." ...only to get shot by Rachel, who has picked up the gun.
 * Thunderball. As Largo is about to shoot James Bond, Domino shoots him from behind with a speargun.
 * In Dragon Ball Evolution, Mai is chasing Bulma and about to deal a killing blow when . A deleted, alternate version of that scene actually has her.
 * The 2010 remake of The Crazies has this happen. Again and again.

Television

 * In the final season of Lost, Jin is about to be attacked by some guys when shows up out of the jungle and shoots them.
 * In the series finale,
 * Happens in the new Battlestar Galactica Reimagined, during the Battle of New Caprica. Galactica is cornered by four Baseships, taking a heavy pounding, its point defence batteries failing and its FTL offline. The crew even realise that this is it. Camera zooms out...and shows a barrage of torpedoes heading for the nearest Baseship, the source being the Battlestar Pegasus.
 * #Mmmm whatcha say?#

Literature

 * Happens more than once in The Wheel of Time, ending the following fights: Rand vs Be'lal, Rand vs Lanfear, Rand vs Rahvin, Nynaeve vs Moghedien (twice), Perrin vs Aram.
 * This happens about once a book in The Pendragon Adventure.

Video Games
"Zidane: Stop trying to show off . You make the rest of us look bad."
 * Uncharted 3-
 * Xenosaga Part 1 combines this with Surprisingly Sudden Death, when KOS-MOS blasts through a wall to save Shion in the nick of time.
 * Zidane saves in this manner in Dissidia Final Fantasy. Then he teases HIM for being a showoff


 * Elain attacks Lechuck this way with the cursed cutlass of Kaflu in Tales of Monkey Island: Rise of the Pirate God, but doesn't work as Lechuck had already absorbed so much power it didn't affect him.
 * Free Space; In the Inferno R1 mod, this is first played straight, then subverted.
 * Played straight as an arrow in the trailer for Guild Wars: Prophecies.
 * In the final dungeon of The Legend of Zelda Twilight Princess, Link is about to get hit by an arrow when "The Group" comes in with a bazooka. Fridge Logic sets in when you remember that Link has survived much worse than a single arrow, but still a cool scene.
 * This trope saves you in  in Quest for Glory

Web Comics

 * Problem Sleuth combines this with Pretty Little Headshots at one point.
 * In Juathuur, Veithel
 * The Inexplicable Adventures of Bob: Jean saves Bob from King Mook of the Bigfeet with a floorlamp.

Western Animation

 * In Thundercats 2011 this serves as Mysterious Protector Cheetara's Dynamic Entry, saving young Prince Incognito Lion-O from a headlock by rapping his mugger in the back of the head with her staff.