The Flash

 The Flash is a comic book superheroes from DC Comics. Created by writer Gardner Fox and artist Harry Lampert, the original Flash first appeared in January 1940. F our different   characters —each of whom somehow gained the power of "super-speed"—have assumed the identity of the Flash:   Jay Garrick   (1940–present),   Barry Allen   (1956–1985, 2008–present),   Wally West   (1986–2006, 2007–present), and   Bart Allen   (2006–2007, 2009–present). The second incarnation of the Flash,   Barry Allen, is generally considered the first hero of the   Silver Age of comic books   and the superhero has remained one of DC's most popular ever since. Each version of the Flash has been a key member of at least one of DC's premier teams: the   Justice League of America.

 The Flash and Batman appear to be Sheldon's favorite superheroes. He has three times appeared as the Flash and often talks about Batman.