Deadly Delivery

A criminal or terrorist poses as a package Courier or mailman to deliver a bomb, or get the target to open the door so he can be shot or kidnapped. The advantages of this are obvious -- by insisting that the target sign for the package, the killer can be sure a) the door gets opened for a stranger, and b) he's got the right man.

Of course, there is nothing to stop the hero from using this technique too, for non-lethal purposes -- see Delivery Guy Infiltration. When the bomb is simply mailed to the target, that's You Got Murder.

See also Room Disservice. An inversion is Shoot the Messenger.

Anime and Manga

 * Rurouni Kenshin. Hajime Saito pulls this stunt when he visits the Kamiya dojo, by posing as a peddler selling medicines and home remedies. Sanosuke almost falls for it, until he notices the calluses on Saito's hands. At which point Saito
 * Saito pulls this again, only hours later, this time posing as a police officer, under the pretense of having heard of the attack from before. Kaoru and Megumi tell him Kenshin's out, so they invite him in. Saito behaves this time -- until Kenshin finally arrives.

Fan Work

 * Done in Ace Ventura Rising through clever editing of actual Ace Ventura footage.

Film

 * Three Days of the Condor opens with a CIA station being wiped out by three assassins. As the station is protected by CCTV cameras, locked doors and a guard — even the receptionist has a gun in the drawer -- the killers get inside by sending in a man dressed as a postman. The place gets regular deliveries of books so this doesn't seem strange.
 * Action Jackson (1988). Used by the Invisible Men to kill a witness, with a silenced gun held behind the Clipboard of Authority.
 * Fright Night (2011): One of the vampires impersonates a delivery person so he will be invited inside and bypass the entry prohibition.
 * The movie version of Thr3e opened with a scene where a girl is given a book by the Riddle Killer from a hot dog vendor. Said hot dog vendor is actually the Riddle Killer, giving her his message.
 * Terminator 2. The T-800 carries a longbox that looks like it's full of roses. And it is, but it's also got a shotgun in it.
 * In The Living Daylights, The Dragon disguises himself as a milkman and a balloon salesman. Both times he kills his targets by strangling them with the chords of his headphones.
 * The villain in Phone Booth.
 * Quick. The title female assassin (Teri Polo) gets into a police safe house by pretending to be a pizza delivery girl. She conceals a pistol under the pizza box.
 * In Léon: The Professional, Mathilda (Natalie Portman) tries this trick to get past the door security at the NYC DEA office.
 * The Mechanic (original). The hitman pretends to be driving one of the chicken delivery trucks.

Literature

 * In Scorpia from the Alex Rider series, Alex himself does this to try to kill Mrs. Jones.

Live Action TV

 * Luther. A gang of home invaders looking to steal diamonds from a pair of white collar criminal who are about to leave the country turn up in an identical removalist van to the one that's just left. Thinking there's been a mistake the man answers the door only to be struck in the face.
 * Chuck: Shows up at least once, when a courier picking up a package decides to also kill the guy he's getting it from.
 * Saturday Night Live season 1. A recurring character is a "land shark" that tries to get people to open their door. He always gets in when offering a candygram.
 * Buffy the Vampire Slayer: In "What's My Line?", Cordelia lets a cosmetics salesman into the house, unaware that he is actually an assassin who can transform himself into thousands of mealworms.

Video Games

 * There's a murderer in Trauma Team who kills her victims by masquerading as a postal worker, then "delivering" a package containing a hidden bomb.
 * In Phoenix Wright Ace Attorney: Justice for All, Career Killer Shelly deKiller disguises himself as a hotel bellboy delivering tomato juice to get into his target's room.

Web Original

 * In the Happy Tree Friends short 'Operation: Tiger Bomb', Flippy, Sneaky, and Mouse Ka-Boom attempt to kil Tiger General this way. Due to Flippy throwing a slice of pizza instead of a knife, it fails.