Publicly? Well, here’s one.
When it was decided to make a Superman movie (the first in decades), the studio wanted star power. Unfortunately, capes and tights were seen as beneath a movie star’s position. Actors were afraid of typecasting, which happened to the likes of George Reeve and Adam West. Still, optimistic producers went to everyone and got flat-out turned down by many big names.
Oh, this guy wanted the role. Went as far as going in to pitch himself to the producers. They thought he was the wrong fit.
All of them (except the last one) were afraid of how the role would affect their status as leading men. (Redford is the exception. He thought he was too famous to be the face of a superhero.) None of them wanted to be seen as Superman. Newman was given the choice of picking who he wanted to play: Supes, Lex, or Jor-El. And was offered more upfront than Brando got. Eastwood gave a very polite but quick hell no.
Of course, any of those actors would’ve given us a completely different movie. Reeves brought freshness to the role because we didn’t know him. He could be the Man of Steel because he wasn’t already Dirty Harry, Hud, or Clyde Barrow.
Keaton and Nicholson turned that fear of typecasting around when they did Batman. And, of course, Marvel Studios made putting “superhero” on your resume a must. I knew the tide had turned when Redford popped up in a Captain America movie.