Self-Sustenance

Summary
Self-Sustenance is the ability to maintain oneself infinitely without the typical requirements of life.

The methodology of this ability may vary greatly, and for certain types of creatures this may simply be a normal aspect of their being - for example, undead creatures generally do not require oxygen. Beings that are incorporeal or possess a similar natural ability would likely have this power.

Types

 * Type 1: Respiratory Self-Sustenance: The ability to live indefinitely without oxygen (or whatever substance that the creature's species breathes). This includes surviving in the vacuum of space or in the depths of an ocean. This may provide resistance to certain gas-based toxins.
 * Type 2: Nutritional Self-Sustenance: The ability to survive indefinitely without food or water (or whatever the species of creature would generally rely on for nutritional value). This may provide resistance to poisons.
 * Type 3: Restful Self-Sustenance: The ability to continue acting forever without rest or need for sleep. These users of this ability require no rest and do not run out of energy, or even feel tired. This ability denotes practically infinite stamina and may support a resistance to certain types of Sleep Manipulation.

Users

 * Superman and many other characters (DC Comics)
 * Frieza, Cell, and Majin Buu (Dragon Ball)
 * Thor and many other characters (Marvel Comics)