Designated Bullet

""When a pirate's marooned, he's a given a pistol with a single shot. One shot. Well, that won't do much good hunting or to be rescued. But after three weeks of a starving belly and thirst, that pistol will start to look real friendly. But Jack escaped the island, and he still has that single shot. Oh, he won't use it, though, save on one man: His mutinous first mate.""

- Mr. Gibbs, Pirates of the Caribbean: Curse of the Black Pearl

Bob has just betrayed Alice and left her for dead, or maybe he's murdered Alice's whole family, or maybe Alice just really wants Bob to die, so much so that she'll throw in a bit of Poetic Justice and designate a special bullet to be used, just for Bob.

This trope is is about getting revenge, but it's not enough to simply get revenge. This is a special case. So special that not just any old bullet will do. No, the bullet Alice uses (or even the gun she uses) must be related to the reason Bob must die. Bonus points if the bullet has Bob's name inscribed on it. It's not uncommon for Alice to craft the bullet from special materials as well.

Subtrope of Its Personal.

Comics

 * In the first issue of the Secret Six miniseries, Deadshot promises Lady Vic that he will save a bullet so that when he does shoot her "it will be like no time has passed at all." Four years later, in the penultimate arc of the ongoing series, Deadshot shoots Lady Vic despite running out of ammo earlier in the issue, indicating that he had been saving the bullet the whole time and didn't use it to save his own life.

Film

 * Pirates of the Caribbean: Jack Sparrow, left marooned with a pistol and single shot to be used for suicide, somehow escaped that island and saved the bullet for Barbossa, whom he didn't see again for over ten years.
 * The Patriot: Benjamin Martin melts down some lead soldiers that belonged to his dead son Thomas in order to make bullets when he starts fighting against the British. The final one of these is dedicated to Colonel Tavington, the Evil Brit who murdered said son..
 * Lethal Weapon: Riggs tells his new partner Murtaugh that he has a special bullet picked out in case he ever decides to kill himself (which he thinks about every day). At the end of the film, . The bullet is stated to be a hollow-point, to minimise the odds of botching the job.

Literature

 * In the Septimus Heap series, there is a magical significance to a named bullet, and sooner or later it will always find its target.
 * The way the bullet is named is important too..
 * In The Anubis Gates, Jacky is out to avenge Dog-Face Joe's murder of Colin Lepovre by shooting Joe with the same gun that killed Colin.

Live Action TV

 * On Life, Charlie is shot, and when he recovers he asks for the remains of the bullet taken out of him. He then melts it down and molds it into another bullet, and shoots the man who shot him.

Theater

 * In Eugene O'Neill's play The Emperor Jones, the tyrant Brutus Jones flees into the forest but is convinced that he is Nigh Invulnerable and can only be killed by a special silver bullet that he possesses. He would rather kill himself with it than be captured, but La Résistance ultimately kills him -- yes, with a silver bullet.

Video Games

 * Starcraft 2: Jim kept a single round in his revolver for Mengsk. Subverted, since when he really needs it he doesn't even hesitate in using it on.
 * A lesser example, bandits in Borderlands sometimes shout "I've bin saving one for ya!" in a firefight.
 * The Fallout New Vegas Gun Runner's Arsenal Add-on adds an achievement called 'Talk about owned', which requires you to kill Benny with the same pistol he shot you with in the beginning of the game. There's also a mod which gives you the opportunity to craft a bullet to use on him, created from the bullet dug from your own head.