The Flash producers have found their speedster. Glee's Grant Gustin has landed the key role of The Flash/Barry Allen in The CW's backdoor pilot and potential Flash spinoff. Gustin will play the iconic comic book character and appear in three episodes of The CW's Arrow -- eight, nine and 20 -- the latter of which will serve as the backdoor pilot for a potential spinoff Flash series. Arrow co-creators Greg Berlanti, Andrew Kreisberg as well as director David Nutter are behind the potential spinoff. Berlanti, Kreisberg and DC Entertainment's Geoff Johns -- a writer/consultant on Arrow -- will pen the script for Warner Bros. Television; Nutter will direct. The potential Flash spinoff will be an origin story similar to what producers did with Stephen Amell starrer Arrow. All three Barry Allen episodes will be penned by Berlanti, Kreisberg and Johns. "When we first meet Barry Allen, he's just a forensic scientist … an ordinary man," Kreisberg tol