Morgan Freeman as Nelson Mandela in Invictus
Watch some videos of Malcolm X speaking, and then watch Denzel. It’s uncanny how close they are.
Another vote for Bruno Ganz as Hitler. As far as I’m concerned, it’s over: the role’s his.
One not mentioned yet is Frank Langella’s portrayal of Richard Nixon in both the play and movie of Frost/Nixon. That Sean Penn in Milk beat out Langella for Best Actor should be added to the list of all-time Academy screw-ups. If not Langella, then give it to Mickey Rourke already…
Derek Jacobi as the emperor Claudius in “I, Claudius”. In fact, pretty much the whole cast (Sian Phillips, George Baker, John Hurt) although I doubt if Augustus was anything like Brian Blessed.
Of course there is the “Beverly Hillbillies” episode “Jethro in the Reserves” where William Mimms plays U S Grant so well in a film shot near the Clampett mansion that Granny mistakes him for the real thing. “He must have a liver made out of cast iron”.