Provi's Health Bars
Adds sleek and expansive health bars / damage indicators. Free Minecraft Java mod for 1.21.11, 1.21.9, 1.21.10.
⬇ Download on CurseForgeAdds health bar damage indicators to Minecraft.
Provi's Health Bars adds both a HUD health bar for your current target and in-world health bars for all mobs. The behaviour of both can be customised extensively in the settings menu.

The HUD health bar changes appearance based on the Entity Group of the mob you're targetting. Other mods can use the API entrypoint of this one to add additional HUD portraits and icons for custom Entity Groups, or even specific mobs.
See the gallery for examples.
Mob Health
Mobs that are mounted are even considered. When viewing a mob that has a mount, a double health bar will be rendered. The mount health even accounts for mob stacking.

Damage and Healing Particles
Fully client-side and configurable damage and healing particles are provided with the mod.
The particles never block your view, they only spawn to the left or right of the mob (relative to your viewing angle).

Provi's Health Bars is a free Minecraft Java mod. Compatible with Minecraft 1.21.11, 1.21.9, 1.21.10, 1.21.8 and newer. Downloaded 1,063,510 times (via CurseForge). Download it and open it directly in the game.