Flesh vs. Brains, the Great Divide

A lot of people fight over what zombies and, naturally, zombie movies are. Zombies have evolved into their popular role from a specific Voodoo practice: Shamans who specialize in relating with the spirit of death are said to revive the recently deceased to do their bidding as a mindless slave, a zombi. Undeath and cannibalism have been addressed in many cultures, for a long time, but the gunshot which started this clumsy zombie race is certainly Night of the Living Dead, 1968. Here we were given the classic rules of zombie films: humans back from the dead are eating other people and a bunch of normal people who don't like each other are stuck to work it out. People often cite 28 Days Later as a zombie film, but why does anyone think that the 'ghouls' in 28 Days are zombies? They aren't slow and they aren't dead or undead. They living people who are infected with rage. And eat normal folks.
There are many reasons that these antagonists feed into our perception of what a zombie is, but one is called Return of the Living Dead, which isn't mentioned much.

If you can get your hands on the dvd of Return of the Living Dead, sink your teeth into the "Designing the Dead" featurette, and watch the movie with the commentary. If you do so, Director Dan O'Bannon shares that:

Night of the Living Dead was written by Russo and directed by Romero.
Afterwards, they split.
Romero went on to direct and write Dawn of the Dead.
Russo went to Warner Bros. with his screenplay, Return of the Living Dead.
This was given to Dan O'Bannon (screenwriter of Alien) to be directed.
O'Bannon felt that this RotLD screenplay was far too similar to Dawn of the Dead,
So, he made some changes: the zombies are fast, semi-intelligent, and brain-eating. Also the movie's more of a dark comedy.

There you have it. Two zombie archetypes from the 80s: slow, super dumb, flesh eaters; and fast, sort-of smart, brain eaters.