The walkers in "The Walking Dead" are fairly standard-issue zombies, all things considered. In fact, depictions of zombies in science fiction and horror are pretty consistent. That's because the term "zombie" has traditionally been used to refer to a specific type of re-animated dead -- the mindless, ravenous walking corpse.
As such, zombies, like skeletons or ghouls, just don't have the narrative range of more sentient and sexy monsters, like vampires or werewolves. But if you dig around (heh) through the canon of zombie stories in movies, books, TV and videogames, you can find some interesting variations on the theme.
Historically speaking, stories of people returning from the grave, in one form or another, are as old as human civilization itself. References to ghosts, zombies and revenants -- in varying degrees of corporeality -- can be found all the way back to early Mesopotamian mythology.