[Varyon]

In the zombie apocalypse campaign I designed (and managed to run all of one session of...), the zombie plague was magitechnological in nature (nanomachines that convert matter into mana, which they used to run), and normal zombies could be divided into shamblers and bleeders. Shamblers were unliving corpses forced to move about by the nanites. They were slow, but highly resilient. Bleeders were either those who succumbed to the plague while living, or were shamblers that the nanites had had enough time to fully repair. They were living, and had some access to their old memories (although for former shamblers the brain was previously damaged enough that pretty much all of this was lost), but were rather controlled by the nanites. They were more fragile than the shamblers, but much faster. Both types were a bit stronger than they were prior to infection, and the bleeders were a bit faster than ordinary humans, but neither were really intended as serious threats - that was reserved for the special undead, basically bleeders that had been remodeled by the nanites to be greater threats. Technically there were shambler variants of each (to represent those that had been killed, but the body not burned, and that the nanites hadn't managed to fully repair), but I never got around to even introducing any of the special undead (and their shambler variants would have likely stayed hidden while under repairs).