Claim: The Flash's basis is Barry Allen.

The Flash is an American television series developed by Greg Berlanti , Andrew Kreisberg and Geoff Johns , airing on The CW . It is based on the DC Comics character Barry Allen / Flash , a costumed superhero crime-fighter with the power to move at superhuman speeds . It is a spin-off from Arrow , existing in the same fictional universe . The series follows Allen , portrayed by Grant Gustin , a crime scene investigator who gains super-human speed , which he uses to fight criminals , including others who have also gained superhuman abilities .   Initially envisioned as a backdoor pilot , the positive reception Gustin received during two appearances as Barry on Arrow led to executives choosing to develop a full pilot to make use of a larger budget and help flesh out Barry 's world in more detail . Colleen Atwood , costume designer for Arrow , was brought in to design the Flash 's suit . The creative team wanted to make sure that the Flash would resemble his comic book counterpart , and not simply be a poor imitation . The series is primarily filmed in Vancouver , British Columbia , Canada .   The Flash premiered in North America on October 7 , 2014 , where the pilot became the second-most watched premiere in the history of The CW , after The Vampire Diaries in 2009 . It has been well received by critics and audiences , and won the People 's Choice Award for `` Favorite New TV Drama '' in 2014 . The series was renewed for a third season in March 2016 , which premiered on October 4 , 2016 . The series , together with Arrow , has spun characters out to their own show , Legends of Tomorrow , which premiered on January 21 , 2016 . On January 8 , 2017 , The CW renewed the show for a fourth season .