When asked how his “The Flash” cameo came about, George Clooney couldn’t help but be flippant, joking that “there was such a clamor for me to come back as Batman. As you know! … Why are you making that face?” He also joked about a notorious costume design choice to add nipples to the Batman, Robin, and Batgirl suits. “They would say ‘Can we do it without the nipples?’ And I was like, ‘Well, that’s not really MY Batman, is it?” Of course, the real question then dropped: “Can they convince you again?” Clooney was blunt:
“I don’t think there’s enough drugs in the world for me to go back.”
Clooney’s cameo in “The Flash” was brought about by a multidimensional conceit that allowed the title hero (Ezra Miller) to run so fast, he could pass into alternate dimensions. Michael Keaton, who played Batman in Tim Burton’s 1989 film, played a substantial role in the film, and the “Flash” finale infamously featured CGI recreations of other famous superhero actors from throughout film and TV history. “The Flash” may have initially meant to open up a vast interdimensional superhero universe, but the DC Extended Universe films have been ended and including Clooney is no longer reasonably viable, even if he was interested.
It’s also worth remembering that Clooney’s two Batman appearances are two of the most notorious failures the studio-backed superhero genre has yet offered. Interest has waned, big-budget movies are tanking, and no one would be excited. Clooney is wise to stay away.