As of 2013, a total of four fictional men are described as having assumed the identity of the superhero known as the Flash: Jay Garrick, Barry Allen, Wally West and Bart Allen. Jay Garrick was the first Flash, who was introduced with the character in 1940. Barry Allen, whose character was introduced to the DC Comics universe in 1956, which is said to be the beginning of the Silver Age of comics, is likely the most familiar iteration of this character to those who do not religiously follow comic book updates.
Barry Allen is the fictional character who takes up the Flash's mantle in most popular adaptations of the Flash narrative. For example, Barry Allen most typically appears as the Flash in live-action adaptations of the story.
Though all of the characters who come to be known as the Flash have super-human speed and a natural inclination toward doing good, each character is shown to have his own personality and individual backstory. For example, Barry Allen and Wally West serve as "Kid Flash," a young assistant and protege to the adult Flash, prior to being promoted to serve as the Flash. Jay Garrick, the original Flash, got his super-speed powers while conducting a science experiment.
Other characters are depicted as having temporarily taken up the Flash's mantle, though not in an official capacity. These characters include a more diverse range of gender and ethnicity than is seen in the main Flash characters, who are all white men.