George Romero invented the zombie genre with 1968's Night of the Living Dead, but he didn't really set out with any goal more innovative than "shoot a horror flick because it beats working in an office." That's why the movie that kicked off the whole zombie craze originally started off as an alien invasion film. The first version of the script was about malevolent extraterrestrials who came to Earth because they liked the taste of human flesh and the Space Arby's was closed.
"Would you like bullets with that?" probably wasn't a line, but should have been.
There was only one problem, or at least only one problem they cared about: money. All of this alien stuff was way beyond their dinky budget, so Romero came up with the ingenious solution of ripping off I Am Legend, and recasting the aliens as flesh-hungry corpses.