Page "Parallel universe (fiction)" Paragraph 110

Because of this, comic books in general are one of the few entertainment mediums where the concept of parallel universes are a major and ongoing theme.

DC in particular periodically revisits the idea in major crossover storylines, such as Crisis on Infinite Earths and Infinite Crisis, where Marvel has a series called What If ... that's devoted to exploring alternative realities, which sometimes impact the " main " universe's continuity.

DC's version of " What If ..." is the Elseworlds imprint.