Young Stars Who Later Played Great Elderly Roles
and actually were old (as opposed to someone young using makeup).
Marlon Brando is my favorite actor, but he didn't play any memorable "old" man roles (He was in his late 40s when he played "The Godfather").
I'm thinking of many great actors but when I think of their roles when they were older, I can't think of anything great.. Kirk Douglas, Burt Lancaster, etc..