The Flash is one of DC Comics' most popular characters and has been integral to the publisher's many reality-changing "crisis" storylines over the years. The original meeting of the Golden Age Flash Jay Garrick and Silver Age Flash Barry Allen in "Flash of Two Worlds" (1961) introduced the Multiverse storytelling concept to DC readers, which would become the basis for many DC stories in the years to come.

Like his Justice League colleagues Wonder Woman, Superman and Batman, the Flash has a distinctive cast of adversaries, including the various Rogues (unique among DC supervillains for their code of honor) and the various psychopathic "speedsters" who go by the names Reverse-Flash or Zoom. Other supporting characters in Flash stories include Barry's wife Iris West, Wally's wife Linda Park, Bart's girlfriend Valerie Perez, friendly fellow speedster Max Mercury, and Central City police department members David Singh and Patty Spivot.