Sliding Scale of Undead Regeneration



Generally speaking, if it's dead, it rots. What's more, corpses become more fragile than when alive (rigor mortis notwithstanding), and it goes without saying that they can't heal injuries or damage.

But what of The Undead? They aren't really dead, but they aren't alive either. So what does that mean in terms of healing? Well, since Our Monsters Are Different, it can mean any of the following along a spectrum of options. Sometimes multiple options if there is a whole undead ecology.
 * TYPE I: No healing, and progressive rotting. Usually the sad lot of Zombies, this set up means that even without human intervention, every zombie will eventually become a moaning pile of bones. In the case of A ghouls and Frankensteins, they might delay the decay by grafting stolen body parts to replace the decayed or damaged ones, which in turn continue to rot.
 * TYPE II: No healing, but no rotting. Much more dangerous for humans, this means that unless dealt with, every zombie is a Perpetual Motion Monster that can last forever in this less than glamorous form of Immortality. The Mummy and his ilk are like this as well. Skeletons and liches have a form of this where they can reassemble themselves.
 * TYPE III: Healing, but progressive rotting. Rare, this set up means the undead decays but can repair injury. This is usually the case of the Technically Living Zombie, who is a human that will eventually die, but until then can heal some wounds.
 * TYPE IV: Healing, and no rotting. The (un)Holy Grail of undead healing. This is usually reserved for the "freshest" and more powerful undead, like vampires. Provided enough blood, they can heal any injury, except perhaps those made by Weaksauce Weaknesses like holy artifacts or sunlight.

It's worth noting that "No Rotting" includes preserving muscles, bones, and ligaments despite everyday wear and tear. This is often implied of many perpetual motion zombies said to never die. Another variant is just how much and how "neatly" the healing is. Some undead just have enough healing to patch themselves up over a long period, leaving massive and ugly cancerous scars. Others have a full on Healing Factor that leaves no scarring, effectively locking their appearance forever.

However, this is never strong enough to bring them back to life, just back to "fresh corpse". Also note that no matter how powerful an undead's healing ability, it is always of the "blasphemy against nature" variety, so Revive Kills Zombie.

Anime & Manga

 * Sankarea: Rea the Moe zombie girl (yes, really) is Type I, with the rotting slowed by consuming hydrangea, part of the drug that made her into one... and staying in a room with the AC turned up.
 * Gungrave: "Beyond The Grave" is a Type III. Unless he receives new supplies of blood daily, his body rots and falls to pieces. The blood also has to match whatever type he was when he was alive
 * Brook of One Piece is a tough example. Similarly to the Arcanum example down in the Video Games section, he took a single-shot resurrection ability. However, it worked much later than desirable, so his flesh rotted off, leaving him a skeleton, thus classifying him as undead... probably. Since then, he survived over fifty years without losing any parts, on an abandoned ship, without eating. He can apparently heal his broken bones... with milk, but is apparently sure he can't regrow his hair if he ever loses it, which he miraculously kept on his skinless skull. So... Type IV, probably.
 * Naruto: Zombie ninja resurrected via Edo Tensei (colloquially 'confetti zombies') are departed souls summoned from the afterlife (Pure World) to the living plane (Impure World) via DNA and ninja magic. They use a living sacrifice as a battery, and the earth and dust constantly surrounding them to emulate their appearance (and genetics) before death, as well as heal any and all injuries/illnesses/missing limbs/etc. Any souls not in the Pure World cannot be summoned, and sealing jutsu that affect souls are still effective on them. Other than that, they can be physically reduced to dust, only to near-instantly recompose themselves. Type IV all the way.
 * In Hellsing, ghouls (walking corpses created when a vampire drains a human of blood) are either Type I or Type II. Vampires are usually Type IV with Weaksauce Weakness, but Alucard can regenerate from things that would kill normal vampires, usually very quickly. However, Alucard is on the border between a vampire and an Eldritch Abomination.
 * In Kore wa Zombie Desu ka?, Ayumu a zombie is a bit of a Type IV with direct sunlight as his Weaksauce Weakness.

Film

 * Death Becomes Her: after imbibing an eternal youth and immortality potion, a person stays alive and can heal whatever a normal person could. But they can't die. When two of the protagonists almost immediately suffer mortal wounds, they just have to patch themselves up. They go on accumulating injuries, and in the Distant Epilogue have started to decay, making them Type II.
 * David's friend Jack is Type I in An American Werewolf in London, and will continue to decay until he is released by the death of the original werewolf.
 * Note that Jack is a ghost rather than a zombie, so his worsening appearance is more a cosmetic issue than a mechanical hinderence.
 * An example of Type III is seen in My Boyfriend's Back. The protagonist zombie is able to regenerate by eating brains, but is otherwise slowly decaying.
 * Romero zombies fall into the second category as demonstrated in Land of the Dead where years after the events of the first movie the zombies still look pretty good.
 * 28 Days Later is type three, as humans infected with the rage virus will heal but will also starve to death given enough time (two month tops). They're technically not undead, just irreversibly psychotic, so they need to eat regularly to survive but lack the intelligence necessary to do anything beyond chasing down animals.
 * The zombies in Dead Heat are an extreme case of Type I. Once resurrected they have about 12 hours before they liquify.
 * In the Return of the Living Dead, the corpses brought back by trioxin gas are (probably) Type I. They eat brains to ease the pain of rotting.
 * In The Crow, Eric gets Type IV, thanks to the titular crow which accompanies him (having brought him back from the dead). But he's brought down to level 2 for the final showdown after one of the villains severely injures the bird.

Literature

 * In the Skulduggery Pleasant series, Skulduggery is of the class two with what appears to be normal healing of injuries to the ghost form around the bones if it is harmed. There is also one mention of an undead being created by the first big bad called the white cleaver, which is class four and a half, as it not only heals, it heals instantly and does not feel pain. the lack of pain likely has more to do with being undead than magic used after it was killed though.
 * Zombies produced by the Zombie Master in the Xanth books are capable of regeneration; they tend to become more human, un-rotting as they spend more time around people and being treated as people.
 * In a short story by Ursula Le Guin, the bite of a certain fly will grant you immortality. After a few centuries' worth of accumulated injuries, you're basically a limbless, faceless torso. Quite a bit longer, and your carbon is compressed into a diamond (which may still be aware).
 * Howard P. Lovecraft's story Cool Air features a rather poignant case of Type I.
 * World War Z (and the previous book by the same author, The Zombie Survival Guide) are unquestionably Type I. Decomposition is slowed because The Virus is toxic to most bacteria, but evidently some can still break down a shambling, undead corpse in spite of infection, decay is explicitly stated to be retarded by cool, dry climates and sped up in hot and humid environments and mention is made of the slow breakdown of muscles because, unlike those of living animals, zombie muscles never repair the wear caused by normal use.
 * Vampires of the Black Court in The Dresden Files fall under "healing but rotting" category. Over time a vampire of this type will gradually rot until they are a dry, withered husk, but this won't really slow them down much. The older a Black Court vampire is, the stronger it gets, and damage to its body (outside of massive obliteration or exposure to its weaknesses like garlic, sunlight, staking, etc.) can generally be healed by consuming flesh from living creatures. A Black Court vampire that gets a limb blown off by a shotgun, for example, will only be moderately annoyed by the loss and can replace it with a quick meal.
 * Jim and the other zombies in Mogworld are type two (possibly type one- most have already rotted before being brought back) having to stitch their various limbs back on repeatedly throughout the novel.
 * Discworld zombies seem to neither rot nor automatically heal (Type II), but they do tend to lose the occasional body part which needs to be stitched back on, and infestation by mice is a concern. One book mentions them smelling of formaldehyde, which may indicate they use mundane preservation techniques.
 * Reaper Man implies that freshly-minted zombie Windle Poons could heal, if he could remember how; zombies no longer have any autonomic processes, and have to "manually" control every aspect of their bodies.
 * The Lifeless of Warbreaker are somewhere between type two and four, they heal, but not as well as a living person, and if they get too badly damaged it's necessary to put more Breath into them to keep them going.
 * The undead of Abarrach in The Death Gate Cycle tend to slowly break down, and their makers have the lost the magic to repair them. Old enough cadavers are essentially just a small heap of bones in a field with a soul hovering mournfully above them.
 * Averted with the lazar who are capable of repairing the damage that they take.

Live-Action TV

 * Torchwood: after dies and is brought back he has to deal with things like a broken finger which will never heal.
 * Vampires in Buffy the Vampire Slayer and Angel are Type IV, having enhanced healing combined with a distinct lack of rotting.
 * Pushing Daisies has a rather strange take, somewhere between Types II and IV. People brought back to life by Ned regain full cognizance and physical capability (or rather, as much physical capability as how intact they are would allow), but their actual bodies are not repaired. A person who has had their head impaled would be brought back with no neurological problems, even while the wound itself remained. A person who has little physical damage or decay would still register as physically dead. And yet all people brought back thus seem to be capable of as much biological process as their bodies allow (capable of things like eating, but unclear whether it is necessary). There's also no further decay, or any change at all (a dog that was knocked down and brought back in the prime of life remains perfectly healthy some twenty years later).
 * Being Human (UK)'s Type IV Supernaturals were actually Type I zombies. The case focussed on rotted progressively, without any healing, but maintained sensation, so she could feel herself rotting, and eventually, feel her joints collapsing and dislocating, her bones breaking, and her . Worse

Tabletop Games

 * Call of Cthulhu (tabletop game). Zombies created using the Gray Binding spell are Type I's.
 * Zombies created using the Create Zombie spell are Type II's, until their caster dies, at which point they become Type I.
 * In Mage: The Awakening magically created zombies gradually decay, to the point where the spell no longer keeps hold. The rate of decay and/or how much decay it takes for the spell to stop working depends on how much power is put into the spell. It is possible to create zombies that can repair themselves by feeding off of other corpses.
 * In Nomine has several variants of undead, mummies and vampires, which fall into Type IV, and zombies which are a variant Type I, they rot unless they can get enough of a certain substance (which varies but is generally brains, blood or similar), and they can be repaired magically although this is normally considered a waste of Essence. Incidentally, Revive Kills Zombie is averted in both cases, due to the fact that the Corporeal Song of Healing will repair non-living (even inanimate) objects as well as living things.
 * The player-character vampires in Vampire: The Masquerade are Type IV. In the sourcebooks and novels, the vampires wake up every night exactly the same as they were when they died (although they of course look thinner and paler). If you had a beard, you can shave it off, but it will return the next night, and so on.
 * The zombies in Palladium's Dead Reign are between type III and type IV. They decay and lose limbs in battle, but these zombies feed off the life-energy released by their victim's deaths (causing them to rise as zombies as well). If the zombie feeds often enough, they can stop their decay, and even reverse it, restoring their damaged flesh as well.

Video Games

 * In Planescape: Torment the undead that reside in Sigil are Type I. The contracted zombies in the Mortuary are kept going with sutures and embalming fluid for as long as they last, but left alone they just decompose until they're skeletal. One memorable quest involves helping a rapidly decaying zombie with identity crisis - all her identifying features are literally melting off and she can no longer remember her name.
 * A character in Arcanum took some kind of immortality potion, but remained trapped in a cave, so by the point you meet him his flesh rotted away, now he's a walking skeleton, making him a Type I.
 * The Necromorphs of Dead Space generally fall under "no healing, no rotting", but the Hunter (artificially created by Dr. Mercer) is completely invincible thanks to its high-speed regeneration abilities.
 * The feral ghouls in Fallout 3 are irradiated humans, not undead. However, there are some known as "Glowing Ones" who can send out a flash of radiation—this injures normal humans, but heals any ghouls it touches.
 * Ghouls in the Fallout series are effectively immortal and are in fact healed by exposure to otherwise fatal radiation. However, this does cause their skin to constantly fester and peel, giving them their perpetual necrotic look.
 * It's stated that ghouls can die of old age, it just is a VERY long time compared to normal humans. They also have other problems to worry about, like eventually going feral due to neurological (or possibly psychological) causes.
 * Raul, a ghoul companion in Fallout: New Vegas, is a Pre-War ghoul, meaning he was alive and well 204 years before the game when the bombs fell. Through conversation with him, we find out a lot about how ghouls actually age. He's got a touch of arthritis (though it doesn't affect his combat prowess), but it's only been bothering him for the past decade or so. The game also implies at least some of it is in his head.
 * Undead units in Gladius can buy a passive ability that lets them regenerate health (quite useful, as undead summoners need spend their own health to power their spells).
 * The various zombie types in Resident Evil are all over the scale, depending on what they're infected with, and how far the disease has progressed.
 * The "infected" in Left 4 Dead and its sequel cannot heal, even by attacking humans and consuming their flesh. But their health bars remain stable when not taking damage, making them Type II.
 * Although basic infected will sometimes randomly puke their guts up or keel over and die of their own accord with no encouragement from player. This leans them towards Type I.
 * This seems to vary between the types of zombies. Smokers can regrow tongues and Chargers develop rock-hard scabs on their arms, implying that they are still healing on some level making them Type III.
 * Dungeon Crawl has three playable undead races (among many others) who each fit differently into the scale:
 * Mummies are a straight Type IV, although things that would mutate the living cause them to rot instead and they can't drink healing potions.
 * Vampires are a Type IV so long as they have blood, but they turn into a Type II if bloodless.
 * Ghouls are a Type III; they can regenerate minor wounds at the same rate as the living (relatively quickly), but their max HP slowly rots away. HP rot can be reversed with meat, preferably rotting.
 * The Forsaken in World of Warcraft are Type III - they obviously rot and movement causes the flesh on their joints to peel off, resulting in their iconic look. But they regain health and can heal rapidly by consuming "compatible" flesh.
 * Death Knights get healing and no rotting after the minor decay that occurred before they were raised... unless they're Forsaken death knights.
 * The zombies and skeletons in Minecraft are both Type II.
 * The zombies and skeletons in Minecraft are both Type II.

Webcomics

 * Uncroaked units in Erfworld can heal damage between turns, but progressively rot. The more experienced the croakamancer, and the more care is put into their creation, the more slowly they rot. Interestingly, they can still gain levels.
 * Those brought back to life by the Arkenpliers, on the other hand, don't seem to rot at all, and may even be able to heal.
 * It's unclear if they can be healed by Healomancy, but it's been all but stated outright that they can be healed by Croakomancy. But once they die again, they go down permanently.
 * The undead race in DMFA get the "no rot, no healing" version. They tend to gradually lose flesh to injuries, but since they're magically animated this is mostly a cosmetic issue. They can also stick severed limbs back in place, and get prosthetic limbs if they lose the originals.
 * The zombies in The Other Grey Meat are subject to wear and tear, but have Limb Replacement Facilities which allow for the replacement of any damage, except for destruction of the cranium. The higher the category, the easier access they have to replacements. The lowest level, Ones, are generally considered a waste of time and neglected, leading to a higher level of decay.
 * The Zombie Hunters contains at least type two, unclear if it is type four for normal zombies. However Charlie, a "Half-Life" (Not quite dead, but not quite alive), is capable of healing his wounds given enough time and sustenance.

Western Animation

 * The Terrorcons in Transformers Prime are Type II, but as they were Mechanical Lifeforms in life, there's no flesh to rot, and may not have been capable of healing themselves while alive, though being reanimated as little more than particularly vicious piles of walking scrap metal means that any of them capable of repairing themselves in life no longer has the mental faculties to do so... and given their viciousness, the idea of anyone else trying to repair them is not even worth considering.