Immortality

Immortality in the cosmere is not actually a thing. However, there are those characters on various worlds who've seemed to achieve it. Brandon has offered the following definitions:
*Doesn't age, but can be killed by conventional means. (Readers have seen some of these in the cosmere.)
*Heals from wounds, but still ages. (Knights Radiant with Stormlight.)
*Reborn when killed. (The Heralds.)
*Doesn't age and can heal, but dependent upon magic to stay this way, and so have distinct weakness to be exploited. (The Lord Ruler, among others.)
*Hive beings who are constantly losing individual members, but maintain a persistent personality spread across all of them. They're immortal in that as long as too much of the hive isn't wiped out, the personality can persist. (The Sleepless.)
*Bits of sapient magic, eternal and endless, though the personality can be "destroyed" in specific ways. (Seons. Spren. Nightblood. Cognitive Shadows, like a certain character from Scadrial.)
*Shards (Really just a supercharged version of the previous category.)
*Hoid (Brandon has not said in which category, if any, he's in.)
Some of these blend together: the Heralds, for example, are technically a variety of Cognitive Shadow.
Brandon hasn't said that each of the categories above are distinct, or intended to be the end-all definitions. They're off the cuff groupings he made to explain a point: immortality is a theme of the cosmere, but each, at their core, are experiments on what happens when men are given the power of deity.Stormlight Three Update #5, /r/Stormlight_Archive, 11/18/16
==References==
Category:Magical Creatures