Robert Duvall. He's a genuine actor,..can assume many roles and play them convincingly.
He was Tom Hagan, the Consigliere of the Godfather. He was Augustus McRae, a Texas Ranger turned trail boss in Lonesome Dove, and Mac Sledge, a washed up country singer who reclaimed a simple way of life in the movie Tender Mercies. He won an Oscar for that role.
He's a pro.