It all began with George A. Romero's Night of the Living Dead
. That movie begat a few sequels and remakes (Dawn of the Dead, Day of the Dead, George A. Romero's Land of the Dead, etc), a series of spoofs (The Return of the Living Dead (Collector's Edition) and 4 sequels), at least one porno (Erotic Nights of the Living Dead) and then more remakes (Night of the Living Dead, Dawn of the Dead (Widescreen Unrated Director's Cut), Night Of The Living Dead 3D), and the nuclear post-apocalypse genre was co-opted by zombies. Movies like "28 days later" and the "resident Evil" series took us there. Then "Shaun of the Dead" gave us the heroic comedy and "Doomsday" gave gave us the tribute pastiche.
Then "Zombieland" came along and gave us the John Hughes road picture zombie movie (which I thoroughly enjoyed, by the way). In the world of the printed word Max Brooks gave us "The Zombie Survival Guide: Complete Protection from the Living Dead" and "World War Z." Comic books gave us everything from Marvel Zombies to Black Gas to Walking Dead to Dead World to Zombie Highway to Jesus Hates Zombies to adaptions of Shaun of the Dean and continuations of Romero's Living Dead franchise. There is even a very clever webcomic called "Zombie Hunters."
And now I know the Zombie Apocalypse has finally, and officially been embraced by the mainstream. It was spoofed in The Simpsons in last night's Halloween episode.