Room Full of Zombies

Almost every zombie film has a scene where the survivors goes into a house or building because it LOOKS safe. But there's that one room someone overlooked. They open the door and a swarm of zombies start to pour out. Usually this happens when people refuse to properly dispose of infected loved ones and they reanimate hours later. Or some refuse to kill their loved ones out of simple grief and decide to hide them in the basement, attic, closet, etc.

Overlaps with Safe Zone Hope Spot, Failed a Spot Check, Creepy Basement, and possibly Blackout Basement.

Comic Books

 * Shows up in The Walking Dead comics when Rick and the crew find a gated community. Also in the beginning of the series during the hospital scene.
 * Also again on the Hershel farm.

Film

 * Happens in both Zombie Diaries films, Twice in the sequel.
 * In Shaun of the Dead this happens when they venture to the pub.
 * The original Dawn of the Dead had a SWAT team raid a housing complex that had their basement filled with zombies. The trope also shows up at a refueling station.
 * Happens yet again in another Romero film, In Diary of the Dead the pool house has zombies at the bottom of the pool. They were corpses at first....But then they reanimate.
 * Discussed in-universe in the film Zombie Apocalypse.
 * In Resident Evil Apocalypse, this happens when the team sent by the Umbrella Corporation unlocks the Hive below Raccoon City in the opening scenes.
 * And again in Resident Evil Extinction, with the clown car trailer full of zombies.
 * In Twenty Eight Weeks Later, one of the infected creates this by

Live Action TV

 * The Walking Dead:
 * In the series premiere, Rick is faced with a room that's been barred shut. Fortunately, the helpful sign on the door, as seen on the trope image above, helped warn him from unsecuring it and letting out the zombies that were behind it.
 * A variation of this also shows up in one of the webisodes on the series homepage.
 * In the X Files episode "Millennium," there are zombies in a basement.
 * Angel has several rooms full in "Habeus Corpus", where the zombies swarm all over the Wolfram and Hart building.

Literature

 * In World War Z South Korea was afraid that this might be the case with North Korea.

Video Games

 * Resident Evil 2:
 * Shows up where you open an unassuming door (in a save room, no less) and zombies shamble in.
 * In one of the RPD's save rooms, there's a fuckload of them in HUNK's minigame.
 * Past a certain point, every time you call the service elevator in the first Dead Rising, the doors *ding* open only to reveal that the car is packed with the undead. In order to use the elevator, you must melee like crazy until they all fall.
 * Because of the way zombies spawn in Left 4 Dead, an otherwise empty house might have a single room packed with zombies or be an area that a zombie horde spawns from.
 * The official comic featured a boat that the cast initially thought as a good means of escape, but was quickly declined since its cargo hold was full of witches.
 * Diablo III has a scene where your character must go in a room like this with a blacksmith in order to assist him in disposing of the infected, including his own wife.