Lithgow is, undeniably, a much bigger name than Rylance, at least in his native U.S.. (Although it’s kind of weird that they’re looking to cast an American actor in the role of one of the iconic British wizards;

The Oscar-nominated star is reportedly "in final talks" to sign up to play the Hogwarts headmaster.

The role is Dumbledore, the most central figure to Harry Potter other than the trio of Harry, Ron and Hermione. But there's a bit of a problem.