There's a lot that's been revealed about The Flash movie to date, including that Ezra Miller's Scarlet Speedster will be joined by Sasha Calle's Supergirl. And that he'll encounter not just one, but two Batmen - both his old mentor, Ben Affleck's version, but also Michael Keaton's Burtonverse Bruce. One thing that's been left unconfirmed, however, is who the film's main villain is. But some intriguing set photos have given rise to a compelling fan theory. One that's now been backed up by a new report.