Invisibility

Invisibility is a status effect that turns entities invisible.

Mechanics
Causes the mob to disappear (except for bosses). Certain features of entities do not disappear: Armor, held items, stuck arrows, any particles emitted, a shulker's yellow head, the eyes of cave spiders, endermen/phantoms/spiders' eyes, a llama's carpet decoration, a pig's saddle and the aura of a charged creeper.

Immune mobs
While no mob is immune to the effect, it is practically ineffective on some mobs.