Immortality

Immortality is an ability that prevents the user from dying, however there are many ways to achieve such a state, as such many different types are required to more accurately describe a characters immortality.

Credit to Character Stats And Profiles for most of the descriptions

Types
Type 1: Characters who can not die by natural means, whether it is from old age, disease, etc, they will have to die by unnatural means such as getting shot in the head, note that this includes people who age but do not die from it, as well as people who don't age at all.

Examples Tet (No Game No Life), Galactus (Marvel Comics)

Type 2: Characters who can survive physical damage, but can not regenerate from them, for example; if a character were to be cut into small pieces but was still alive, however they could not regenerate from those small pieces, that would qualify for Type 2.

Examples Hidan (Naruto), Denji (Chainsaw Man)

Type 3 : Characters who have regeneration to the point where they can mostly not be killed, note that any kind of regeneration does not qualify, most of the time you need Mid level or higher, however most importantly; their regeneration has to be a passive thing that does not require any energy, like a regeneration that will go on forever.

Examples: Majin Buu (Dragon Ball), Doomsday (DC Comics)

Type 4 : Characters capable of coming back from the dead, simply put if they die, they can come back to life, this also includes characters who can come back to life in someone else's body. They technically can be killed, but they will come back to life afterwards.

Examples: Yhwach (Bleach), The Avatar (Avatar: The Last Airbender)

Type 5 : Characters who are unbound by death, or do not exist at all, and thus can not die, usually abilities such as Existence Erasure are required to kill characters with Type 5.

Examples: Oryx The Taken King (Destiny), Griffith (Beserk)

Type 6 Characters who don't have a singular physical form, or a body. Such characters typically use abilities such as possession to transfer their consciousness, soul, spirit, concept, mind, etc, to live on. These characters can rarely even posses inanimate objects. This is more than just conventional possession, as they are not only capable of taking control of someones body, but they can use another body as a host. Usually, the characters original body can be killed, however as long as enough remains to the point where they can possess another body.

Examples: Orcohimaru (Naruto), Jason Voorhees (Friday The 13th)

Type 7 Characters who can not die due to already being dead. Usually characters with this immortality will also have other types of immortality to go along with this, like for example zombies will most of the time have 1, 2, 7, and sometimes 3.

Examples: Dio Brando (Jojos Bizarre Adventure), Itachi Uchiha (Under the Reanimation Jutsu) (Naruto)

Type 8 Characters who are incapable of being killed as long as a certain object, person, concept, etc, exist. If this thing that they are reliant on was to be destroyed, their immortality would also be gone.

Examples: Reinhard Heydrich (Masadaverse), Melzalgald (One Punch Man), Hades (Saint Seiya)

Type 9 Characters who's true body is separate from the realm they can be killed. For example, the concept of apples won't be destroyed if you destroy a singular apple, it is similar with Type 9, where even if you kill their mortal form, that does not mean destroying it's true form.

Examples: Yogiri Takatou (Instant Death), Pennywise (Dark Tower)

Type 10 Characters that are neither dead nor alive, these characters are metaphysical, and as such they are outside of reality, dimensionality,and temporality completely.

Examples: Darkseid (DC Comics), Azathoth (Cthulhu Mythos)