|Cell regenerating a lost limb|
Regeneration or "regen" is a term given when a particular character can heal from wounds at an accelerated rate. Regeneration has different levels. The lowest levels of regeneration basically just increase your body's natural healing ability somewhat, so a wound that would normally take weeks to heal would take days or hours. More advanced forms of regeneration can regrow lost body parts, such as fingers, arms, legs. Even greater forms can regenerate after being decapitated or blown into pieces, and it goes up from there. It is also sometimes known as a "healing factor".
Low: Faster healing ability for normal wounds. In machines and vehicles, this would be regenerating basic exterior damage.
Boy Blue from Vertigo Comics, Naruto Uzumaki from Naruto
Mid - Low: Able to heal wounds that would normally leave large scars. In machines and vehicles, this would be regenerating damage that would normally leave large dents and openings.
Example: Blade from Marvel Comics, Kankel from Betterman
High - Low: Able to regenerate some severed body parts like fingers, arms, legs. In machines and vehicles, this would be regenerating some interior damage, and some minor critically damaged or destroyed parts.
Example: Inuyasha from Inuyasha, several incarnations of Godzilla from Godzilla
Low - Mid: Able to regenerate limbs and from fatal wounds. Still die from loss of vital organs such as the heart and brain. In machines and vehicles, this would be regenerating minor parts and more extensive internal damage.
Example: Isley from Claymore, Orochimaru from Naruto
Mid: Able to regenerate from loss of vital organs such as the heart and brain. In machines and vehicles, this would be regenerating from the destruction of critical parts such as the engine.
Example: Piccolo from Dragon Ball, Kagato from Tenchi Muyo!
High - Mid: Able to regenerate from being blown into pieces
Example: Dio Brando from Jojo's Bizarre Adventure, Bebi from Dragon Ball GT, Victor from Busou Renkin
Low - High: Able to regenerate from a puddle/drop of blood, or a small piece of your body
Example: Alucard from Hellsing, Cell from Dragon Ball, Homunculi from Fullmetal Alchemist, Remilia Scarlet from Touhou
Mid - High: Able to regenerate from being vaporized/dust
Example: Majin Buu from Dragon Ball, The Incredible Hulk (Depending on incarnation and portrayal) from Marvel Comics
High: Able to regenerate from a single molecule/atom/particle
Example: Anthrax from Bastard!!, Lobo from DC Comics, Cherubimon Virus from Digimon
Low - Godly: Able to regenerate as long as your disembodied consciousness exists, such as in the form of your soul or mind, or from other realms.
Example: Doctor Manhattan from Watchmen, Spawn from Image Comics, Dark Schneider from Bastard!!
Mid - Godly: Able to regenerate even after every aspect of the body, mind and soul are erased from existence.
Example: Karukinos from Heroic Age, Milleniummon from Digimon, Doomsday from DC Comics
High - Godly: Able to regenerate even if your existence is erased and the reality you are within is also destroyed.
Example: Swamp Thing from DC/Vertigo Comics