The real, magic kind. The current trend of either scientifically explainable, or scientifically killable zombies, are grossly misrepresented.
True zombies are magically raised by a “Zombie Master,” via arcane ritual, and therefore the entire body is sustained independent of standard biological explanation. These “true” zombies also do not crave brains or even human flesh, unless their master instructs them to do so. They are %100 slave workforce.

Also, the two buddies in “Idle Hands,” which were the awesomest undead guys ever.