Immortality is the term given to people who cannot die from natural means, whether this be due to longevity, regeneration, or other means.
1: Longevity: Characters gifted with this type of immortality cannot die from natural causes, such as old age or conventional illness, but can be killed by unnatural causes.
2: Immortality without regeneration: Characters with this degree of immortality can survive a high degree of physical damage, though they cannot regenerate from it either.
3: Immortality via regeneration: Characters with this type of immortality can simply regenerate damage, though the usefulness of this type depends on the degree of regeneration.
4: Immortality via protection from a deity: This kind of immortality is granted by a god, or a similar entity. Only a being of greater power than the god in question can override it.
5: Perfect Immortality: Complete and utter inability to ever die. This is typically reserved for questionable omnipotents and cosmic characters who are strong enough that dying isn't exactly high on their list of worries, even if they were capable of it.
- Examples: Azathoth (Cthulhu Mythos), Kami Tenchi (Tenchi Muyo!), The Creator (Umineko no Naku Koro ni)
6: Parasitic: The person attains a sort of immortality by bodyhopping, transferring their soul to another body.
- Examples: Teridax (Bionicle), Jason Voorhees (Friday the 13th), Orochimaru (Naruto), Darth Sidious (Star Wars Legends)
7: Undead: Self explanatory. The undead generally double up with other types of immortality, often being impossible to kill through conventional means.
8: Reliant Immortality: The power to be immortal so long as a certain object, person, concept etc. exists.
- Examples: Voldemort - reliant on Horcruxes (Harry Potter), Fairies - reliant on aspects of nature (Touhou Project), AIM Burst - reliant on the Level Upper Network (To Aru Majutsu No Index), Chara - reliant on the concepts they embody (Undertale)
9: Transcendental Immortality: Characters whose true selves exist independently from the plane where they can be killed. For example, a conceptual being doesn't die even if its body, soul, etc will be erased from existence.
10: Meta-Immortality: Entities that are not alive or dead in a conventional sense, standing outside the ordinary laws of reality, temporality, and dimensionality (of any number). If it is possible to destroy such a character, it can only be accomplished by a being of a similar or higher existence.
- Examples: All 1-A characters