When making a melee attack against a creature that reduces it to 0 HP the attacker can declare the attack incapacitating rather than lethal: "the attacker can make this choice the instant the damage is dealt. The creature falls unconscious and is stable." (PHB p.198, "Knocking a Creature Out")

Does this work on constructs and undead? Let's look at the specific cases of Animated Armor (MM p.19) and Zombies (MM pp.315-316):

  • neither require sleep by dint of their Constructed or Undead Nature;
  • neither is immune to the unconscious condition;
  • in case it matters, neither undead nor most constructs are susceptible to Sleep. (Undead are called out by name, most constructs inherit Sleep immunity from their immunity to being charmed. Modrons, however, are not immune to being charmed and thus not immune to being put to Sleep.)

For both creatures sleeping just isn't a thing they do. But it would appear that you can knock them out with a well-placed tap on the back of the head/helm? (It gets even stranger when you start thinking about extending this thinking to a Flying Sword (MM p.20) or a Ghost (MM p.147).)


1 Answer 1


For Constructs (such as Animated Armor), no.

Monster Manual pg.19 covers this.

Constructed Nature.

An animated object doesn't require air, food, drink, or sleep. The magic that animates an object is dispelled when the construct drops to 0 hit points. An animated object reduced to 0 hit points becomes inanimate and is too damaged to be of much use or value to anyone.

As for golems, which are much more powerful construct, the answer is still no.

Monster Manual pg.167 covers this (emphasis mine):

Blind Obedience.

When its creator or possessor is on hand to command it, a golem performs flawlessly. If the golem is left without instructions or is incapacitated, it continues to follow its last orders to the best of its ability. When it can't fulfill its orders, a golem might react violently-or stand and do nothing. A golem that has been given conflicting orders sometimes alternates between them.

A golem can't think or act for itself. Though it understands its commands perfectly, it has no grasp of language beyond that understanding, and can't be reasoned with or tricked with words.

As for undead, yep, nothing seems to prevent that.

So I looked up ghouls, ghosts, skeletons, and zombies to see if any of them had the 0 HP limit like armor does. The answer is no. Interestingly enough, the skeletons can even use their brain and think through rudimentary problems. It seems undead have a little more agency in 5e. So it looks like you could knock out an undead, which makes sense. I mean, vampire spawns are undead, and they sleep, which means they have an unconscious state. Even mummies sleep until you step into the plot device that wakes them up.


Helmed Horror - MM pg.183 (Intelligent construct). It has Constructed Nature, but does not become useless armor at 0 HP as it is not explicitly stated. You could of course rule that Constructed Nature makes it that way, however a Helmed Horror is specifically imbued with actual Intelligence.

  • \$\begingroup\$ I'd say no with respect to Modron's because they disintegrate at 0 HP. I know it says when they "die" but because they're constructs they don't actually die. They're rendered unserviceable to be technical. In addition, being a hive mind, there wouldn't really be a way to knock one out unless you had access to the Primus. As for vampires, literally the first sentence in their entry is: "Awakened to an endless night, vampires hunger for the life they have lost and sate that hunger by drinking the blood of the living." And then later, a section called Born from Death. \$\endgroup\$ Commented Mar 9, 2016 at 6:10
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    \$\begingroup\$ @Lino Frank Ciaralli - not sure how you got there on golems. Nothing you quoted discusses what happens at zero hp. \$\endgroup\$
    – Jack
    Commented Mar 9, 2016 at 12:07
  • \$\begingroup\$ I think the portion I've highlighted under Blind Obedience covers that very well. The conscious part of a golem isn't the actual physical construct, and as such you can't knock the construct out. The controlling factor, yeah probably, but not the construct itself. Without consciousness, you can't be knocked unconscious. \$\endgroup\$ Commented Mar 9, 2016 at 18:49
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    \$\begingroup\$ Hmm, Vampires can't be knocked out because dropping them to 0 HP activates their Misty Escape ability. Also, I don't think you can necessarily draw a line between sleeping and the ability to be incapacitated. Elves don't exactly sleep but can be knocked out. \$\endgroup\$
    – Tim Grant
    Commented Mar 9, 2016 at 20:00
  • \$\begingroup\$ Ah yes, Misty Escape, thank you for that. Vampire Spawns can be knocked unconscious, there's no misty escape for them. Corrected above. The sleep thing was just an example of an unconscious state. \$\endgroup\$ Commented Mar 9, 2016 at 21:42

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