The Worldbreaker Hulk is the strongest and most violent of all Hulks. Created by a cocktail of gamma radiation, cosmic radiation, and Bruce Banner’s own anger issues, it was originally tame enough for Banner to maintain complete control over his transformations as he pleased–although this may just be part of an illusion created by The Leader to keep the creature from ever breaking free.
As The Leader predicted once he could no longer control him, Worldbreaker eventually proved too strong for Bruce Banner to contain at will and world-jumping stakes followed as the creature on occasion broke free in different universes.
Worldbreaker is known primarily for its unrivaled levels of power and brutality towards nearly anything that stands in its way.
