The Flash is supposed to be about, well, The Flash. However, trailers for the movie have put Michael Keaton's Batman front and centre, with the idea clearly being to pull the spotlight away from the troubled Ezra Miller and cash in on Hollywood's current obsession with nostalgia.
Warner Bros. originally planned to have Keaton become the DCEU's new Dark Knight, appearing in Batgirl, Crisis on Infinite Earths, and even a possible Batman Beyond project. That might explain why the actor was so crucial to filmmaker Andy and Barbara Muschietti's plans for The Flash.
"We were, of course, [filled with] blind confidence that you have when you’re developing a movie and you get excited about ideas like this," he told Gizmodo when asked if there was ever a backup plan. "[It] just pushes you forward."
"We were all excited believing that having Michael Keaton as Batman would be a great thing in the movie. And also, I think we all believed that he would be excited about it. And he was."
Producer Barbara Muschietti adds, "And in moments like that you just have to lean in. As we sat with him at a lovely lunch, we told him that we couldn’t make the movie without him. And he boarded the train."
Ben Affleck plays a minor supporting role in The Flash, but it wouldn't have made a huge amount of sense for him to have been this new reality's Dark Knight. Val Kilmer is unable to return due to ill health, while there's no way George Clooney is ever reprising this role for more than a cameo at most.
There was always Christian Bale, of course, but he's said on multiple occasions he'll only be Batman again if Christopher Nolan is at the helm. Could Jeffrey Dean Morgan have played the Thomas Wayne Flashpoint Batman? Yes, but that movie doesn't exactly have the makings of a massive box office draw, unfortunately.
The Flash is set to arrive in theaters on June 16.