Dead

A creature is Dead when it has been reduced to 0 hit points and one of the following occurs:

• Failed death saves: A player character at 0 HP rolls a death saving throw at the start of each turn. Three failures (cumulative; need not be consecutive) and the character dies.
• Massive damage: If a creature takes damage equal to or greater than its hit point maximum on top of being reduced to 0 HP from a single source, it dies instantly. (A creature with 30 max HP at 5 HP that takes 35+ damage in one hit dies outright.)
• Effects that kill outright: Spells like power word kill, finger of death (under some conditions), and certain monster abilities can kill without going through the death-save sequence.
• NPCs and monsters typically die at 0 HP without rolling death saves — the DM may choose to grant a save in narratively meaningful cases.

Mechanical consequences:

• A Dead creature drops everything it was holding and falls Prone
• It cannot take actions, reactions, or be the target of effects that require a living target
• It is no longer a valid target for healing spells; raising it requires Revivify, Raise Dead, Resurrection, True Resurrection, Wish, or DM-authored revival
• Time matters: most revival spells have time limits measured from the moment of death

Stable but not Dead: A creature at 0 HP that succeeds three death saves becomes stable — unconscious but no longer dying. See Death Saving Throws.