/damage

Applies a specified amount of damage to targeted entities, with optional damage type and source entity.

Syntax

/damage <target> <amount> [<damageType>] [at <location>]
/damage <target> <amount> [<damageType>] [by <entity>] [from <cause>]

Name	Required	Description
target	Yes	The entity/entities to deal damage to.
amount	Yes	Amount of damage to apply (in half-hearts).
damageType	No	The damage type identifier (e.g., `minecraft:mob_attack`, `minecraft:fire`). Affects armor, enchantment resistance, and death messages.
entity	No	The entity to credit as the direct attacker (used with `by`).
cause	No	The entity to credit as the indirect cause (used with `from`).
location	No	The coordinates for location-based damage (used with `at`).

/damage @e[type=zombie,limit=1] 5
/damage @p 3 minecraft:fire
/damage @e[type=pig] 10 minecraft:mob_attack by @p

Requires permission level 2.
Added in Java Edition 1.19.4 (snapshot 23w06a).
The damage type determines how armor and enchantments reduce the damage, as well as which death message is displayed.
Using by and from can produce correct death messages referencing the attacker.
Damage types are defined in the data pack's damage_type registry.