Keaton plays Riggan Thomson, an actor who became a household name for playing The Birdman, a comic book superhero. But the role haunts the rest of his career. We find him as he's trying to mount a comeback on Broadway, to prove to his fans that he's more than just an actor in a crazy costume.
"So, it's not autobiographical, but it's pretty darn close; it's weird," said Cowan.
"Oh yeah! Of course, yeah, it's amazing."
The part wasn't written for or about Keaton; it's an odd coincidence.
"I probably relate less to this character than anybody I've ever done, that's the irony," Keaton said. "I'm not, I've never been that."
"You don't have that voice in your head telling you, 'You need to be...'"
"I've got other voices in my head!" he laughed.
He is, truth be told, Michael Douglas (that's Keaton's real name), born the youngest of seven in Pittsburgh in 1951.
"I was pretty funny," Keaton said. "And I must have liked the attention. It's weird, 'cause I actually don't like attention. But I must have liked the attention."
His first exposure to show business came in the neighborhood - "Mister Rogers' Neighborhood," to be exact, as a prop man at PBS station WQED. But Fred Rogers was neighborly enough to give a struggling actor a chance in front of the camera, too.
Michael Douglas only changed his name to Michael Keaton because there were two other Michael Douglases that were just a little more famous at the time.
It wasn't his name that got him noticed, but his frenetic energy, in the film "Night Shift." He had a certain charm that made him perfect for playing likeable wise-guys.
And when "Mr. Mom" came around, casting Keaton seemed a no-brainer. He was witty, dry, and especially funny.
But Keaton could also do drama, whether as a coke addict in "Clean and Sober," or a sociopath in "Pacific Heights."
"I like to let the reins out," he said. "I like to have the bit out of my mouth, you know? I like to run, 'cause it feels good. So you know, I'm fairly fertile."
Somewhere in that fertile mind of his, he found what director Tim Burton was looking for, for the character of Beetlejuice.
"Frankly, I don't, to this day I couldn't tell you what his idea was exactly," Keaton said. "I developed a walk. And I created a kind of talk. And I asked for fake teeth. That was free rein. 'Cause you can never say, 'My character wouldn't do that.'"
But when it came time to play the Caped Crusader, even some of his fans balked. The good-natured funny man, they feared, would never be dark enough to play the Bat.