Does dying cause a creature explicitly to drop to zero hit points?

Question

The typical way to die involves dropping to zero hit points first.

But if something such as Power Word Kill, kills a creature instantly, is it specified in the rules that the creature “drops to zero hit points” ?

To clarify, I understand that dead means dead, and dead creatures do not get to make death saving throws. The question is, does the act of a creature dying make its hit point total zero?

Or can a creature simply “die” (and then, perhaps, have no hit point total?) thus skipping any effects triggered "when [this creature] drops to zero hit points."

The recent question about Paladin’s Steed is the inspiration for this question. I know I would rule that getting dead means going to zero hit points — I just haven’t seen that said as much in official material.

Answer 1

Power Word: Kill does not.

Power Word: Kill just checks to see if you have less than 100 hit points. (If you're familiar with the rules of Magic: the Gathering, it's sort of like a state-based action.) If you do, you just die, making your hit point total irrelevant, as you don't get any death saving throws. You're not unconscious, you're just dead.

If the creature you chose has 100 hit points or fewer, it dies. Otherwise, the spell has no effect.

Answer 2

I haven't been able to find a Sage Advice answering this question, though there is one about what happens when wild-shaped druids are targeted by Power Word: Kill. The druid reverts, but in that case, the wild shape ability explicitly says you revert "if you drop to 0 hit points, or die". This might be a hint that they don't drop to 0, since if they did, the "or die" section would be redundant.

Otherwise, looking at the rules text, it seems like the rules only specify how it works in the other direction:

When you drop to 0 hit points, you either die outright or fall Unconscious

However, the top of the Damage and Healing section has this text:

Hit points represent a combination of physical and mental durability, the will to live, and luck. Creatures with more hit points are more difficult to kill. Those with fewer hit points are more fragile.

A creature’s current hit points (usually just called hit points) can be any number from the creature’s hit point maximum down to 0. This number changes frequently as a creature takes damage or receives healing.

It could be argued from this section that, since creatures have hit points, and the (newly-dead) corpse is no longer a creature, they no longer have a hit point total because they're dead.

Conversely, Revivify starts with the text:

You touch a creature that has died within the last minute.

which might mean that dead creatures are still considered creatures.

Ultimately, there isn't an explicit answer to this question, so the answer of how this works at your table is going to be up to the individual GM.