Can a Necromancer reuse the corpses left behind from slain undead?

Question

I’ve recently been doing some builds for Necromancers for a one-shot we’ll be doing. I have been struggling to find anything that mentions how to keep up with all of the corpses you will need for the Animate Dead and Create Undead spells.

There seems to be an indefinite period a corpse can stay a corpse within the 5E RAW.

I also haven’t found anything stating that undead that are killed again cannot be animated again, within RAW.

Once my zombie or skeleton dies and becomes a corpse again, may I reuse the now corpse according to RAW?

Answer 1

Maybe for skeletons, but other undead probably can't be re-reanimated

It's important to note that the spells you mentioned can create undead minions out of a specific type of remains: not just any kind of corpse can be animated by these spells (you can't raise an undead dragon or minotaur with them, for example): they are specifically designed to create undead out of dead humanoids.

The spell create undead contains the following text (PHB p. 229; bold added):

Choose up to three corpses of Medium or Small humanoids within range.

The spell animate dead has a similar requirement (PHB p. 212; bold added)

Choose a pile of bones or a corpse of a Medium or Small humanoid within range.

It might not be obvious why this matters at first. It might seem that if you raised a zombie from a corpse of a humanoid, and then that zombie was destroyed, the resulting new corpse is still a dead humanoid. But a destroyed zombie or ghoul is not a humanoid corpse: it is the corpse of an undead!

As such, most destroyed undead are not valid targets of the animate dead or create undead spells.

Why might skeletons be an exception?

The text of animate dead is somewhat grammatically unclear about its possible targets. At first glance, it seems that the "pile of bones" or "corpse" must both have belonged to "a Medium or Small humanoid." But if we delete the term about the corpse, the resulting sentence:

Choose a pile of bones [...] of a Medium or Small humanoid within range.

becomes grammatically awkward. The pile is the thing being said to be "of" the humanoid, which is strange since humanoids don't contain piles of bones. If they had said "a pile of the bones of a Medium or Small humanoid", or "a pile of bones from a Medium or Small humanoid", it would have removed this grammatical awkwardness (by stressing that the bones, not the pile, are the thing once inside a humanoid). But this is not the structure of the sentence we are given.

However, there is one other way to remove this awkwardness, which is to assign the "humanoid" requirement only to the corpse, not the pile. This makes the sentence regarding the pile of bones less awkward, like so:

Choose a pile of bones [...] within range.

This is a grammatically valid reading of the original sentence, given its ambiguity (and the grammatical strangeness of the other reading). Thus, you could conclude that the bones could come from creatures other than humanoids, such as an undead.

Note that your DM may take issue with this reading. After all, it could permit you to animate a skeleton from a pile of bones from a mouse or a dragon, which is likely outside of the scope of the intended use of this spell. And since the RAW on this issue rely on an ambiguity, your DM will need to sign off on this. But if they do, you could possibly use animate dead on a destroyed skeleton to restore it to a foul semblance of life once again. After all, although the pile of bones are no longer the bones of a humanoid, they are certainly still a "pile of bones."

Sage Advice backs up these interpretations

A recent (2020) addition to the Sage Advice Compendium addresses this issue directly. It provides a question and answer on page 15 (question in bold, italics added for emphasis):

Can I cast animate dead on the humanoid-shaped corpse of an undead creature such as a zombie or a ghast? When animate dead targets a corpse, the body must have belonged to a creature of the humanoid creature type. If the spell targets a pile of bones, there is no creature type restriction; the bones become a skeleton.

Thus we have explicit RAW support for the above arguments. A pile of bones from an undead creature (such as a destroyed skeleton) can be re-reanimated, but a corpse (body, not just bones) of another formally undead creature (e.g. a zombie) cannot be re-reanimated with animate dead.

Answer 2

Unfortunately, no by wording from sourcebooks*. But please read through for a full explanation.

Animate dead (PHB, 212) states that the spell requires (my emphasis):

a pile of bones or a corpse of a Medium or Small humanoid within range.

Once a dead humanoid is turned into a skeleton or zombie, they are no longer humanoids, but undead. Their form may be that of a humanoid, but their creature type is not. When creature types are mentioned, such as in this spell, that is the requirement.

A pile of bones that was previously an undead is now a corpse of an undead zombie or skeleton - not a corpse of an dead humanoid.

As they no longer have the humanoid type, they are no longer valid targets for animate dead.

Without a mechanic that all undead creatures who were once humanoid revert to being a humanoid at death, their creature type remains from what they were when they died: undead.

Now no longer with Sage Advice compendium support!

The Sage Advice Compendium confirms this interpretation:

Can I cast animate dead on the humanoid-shaped corpse of an undead creature such as a zombie or a ghast? No. Animate dead targets only the corpses of creatures that have the humanoid creature type.

But the Compendium was updated...

*Now with updated Sage Advice Compendium which ALLOWS THIS INTERACTION

The Sage Advice Compendium has been updated to now state:

When animate dead targets a corpse, the body must have belonged to a creature of the humanoid creature type. If the spell targets a pile of bones, there is no creature type restriction; the bones become a skeleton.

Is a pile of bones separate from corpse of medium or small humanoid?

It could be interpreted as a [pile of bones] is completely separate from [a corpse of a small or medium humanoid], but that seems kinda strange.

It means you could take the corpse of a large humanoid, remove the flesh, and now all of a sudden it's a legit target? That doesn't seem like the intent and the reading that the bones or corpse must be of a medium or small humanoid makes more sense.

GM's choice

As always, a GM can allow the reanimation of the bones or corpse of an undead. I don't think it'd be massively imbalanced, and would help those who use those types of spells to re-use their undead army.

Personally, I'd allow reanimation of raised/animated undead by PCs (or NPCs). It's weird and seems like it would punish those who want to use necromancy like this to have their creations be single use.

I'm glad that Sage Advice updated to reflect the common sense here that I would have ruled, but this is a good example that just like tweets before them, the Sage Advice Compendium are rulings that may change. You can use them to help guide your own rulings, but please remember that those answers can be as fallible as the original editing.

Answer 3

Yes you can if the corpse was a humanoid at some point.

Per the Sage Advice Compendium:

Can I cast animate dead on the humanoid-shaped corpse of an undead creature such as a zombie or a ghast? When animate dead targets a corpse, the body must have belonged to a creature of the humanoid creature type.

If the spell targets a pile of bones, there is no creature type restriction; the bones become a skeleton.

Skeletons are clear, any bones can become a skeleton.

About the zombie, sage advice requires that the body/corpse must have belonged to a creature of the humanoid creature type. There is no limit as to how far in the past that might have been. So if you target the corpse of a zombie, that zombie must have been created from the corpse of a humanoid. Or there could be more zombie steps in-between, but originally the body must have belonged to a creature of the humanoid creature type.

If you target the corpse of a zombie, that was created from a dead minotaur or something similar, you cannot create undead from it.

Thanks to to the other answers for the excellent link, I did not know you could link to exact pages in a pdf.

Answer 4

Yes you can, for both corpses and skeletons.

Per the Sage Advice Compendium:

Can I cast animate dead on the humanoid-shaped corpse of an undead creature such as a zombie or a ghast? When animate dead targets a corpse, the body must have belonged to a creature of the humanoid creature type. If the spell targets a pile of bones, there is no creature type restriction; the bones become a skeleton.

In other words, just make sure it's the right shape for corpses. For skeletons, it doesn't matter.

This is confirmed in Jeremy Crawford's response tweet:

Is there anyway for an undead minion to be healed. Necromancer doesn't want his minions dying so is it possible? Undead minions can receive temporary hp and can spend HD during a short rest. And animate dead can bring them back!