The user is immune to almost all kinds of damage, be it physical (internal or external), mental, spiritual and even conceptual. The user can be immune to all those damage except for one or more exceptions.
The Infinite Orb (Anima: Beyond Fantasy) its immune to any form of instant death or destruction, and the more than one can do is deactivate its defensive system temporaly; only beings not bounded by the Nexus of Souls can truly destroy it.
The Golden Turd (American Dad!) can only be destroyed by returning to its source, Roger Smith.
Alien X (Ben 10: Omniverse) is immune to all damage including the destruction of the entire universe around him and everything in it; however, he can be harmed by another member of his species.
NRG (Ben 10 Series)
The Worst (Ben 10: Omniverse)
Brandon Breyer (Brightburn)
Road Kamelot (D.Gray-Man) is totally immune and safe, due to her true form is in her Dream dimension, in the outside world she can make a duplicate of herself to go anywhere, without using her true form.
Kryptonians such as Negative Supergirl (DC Comics) share an immunity to their individual Heat Vision.
Barbatos (DC Comics) is nearly invincible and cannot be defeated through normal means however, the Nth Metal and the Element X can harm him.
Despite having a shield, Crota (Destiny) is immune to all damage except for when hit by an Ascendent Sword.
Being the Death Dragon, Acnologia (Fairy Tail) is immune to all kinds of magic, save for other dragons.
Leprechonians (Monsters vs Aliens) are a race of Leprechaun-like aliens that can manipulate probability, inducing good luck or bad luck on others.
The Tick (The Tick)
Two-Ton Tunic (Xiaolin Showdown) makes the user invulnerable to physical attacks plus indestructible.
The Five Headed Dragon (Yu-Gi-Oh!) is immune to attacks from all but Light or Divine monsters.