Many Different Types of Zombies

I am not the biggest fan of zombie movies, most of the ones I have seen have been grotesque and that is not entertainment for me. But this site I stumbled upon shows a different dimension to the zombie- like philosophical zombies, voodoo zombies and Hollywood zombies. The website also offers a theory on where zombies may have originated. It says that some zombies may have come from ancient beliefs on ghosts seeking vengeance. At least if offers an explanation, I don't like how Land of the Dead offered no explanation as to why the zombies were even there.