In Birdman, Michael Keaton plays Riggan Thomson, a veteran film actor who is eager to rebuild his reputation. Like Keaton, Thomson is largely remembered for playing a superhero 25 years ago. And, like Keaton, he has spent much of the intervening quarter of a century explaining why he abdicated from that role – in Thomson’s case, Birdman 4; Keaton, meanwhile, turned his back on Batman.