I agree with the fact that Gary Oldman is an unnaturally gifted actor, but the issue is that he has never been part of a iconic project that makes him irreplaceable. It is the same reason I did not include Meryl Streep in my list for actresses.
Daniel Day-Lewis
Joaquin Phoenix
Anthony Hopkins
Robert De Niro
John Malkovich (If he was more selective with he's films, he'd be widely regarded. But I still consider him a beast.)
RIP - (worthy mentions):
James Stewart
Marlon Brando
Laurence Olivier
I think it's harder to choose my favourite actresses because there are so many I love. Either way, I'll probably regret posting this because I'll end up changing my mind. Throw in Arnold Schwarzenegger for shits and giggles
Charlie Chaplin - The Great Dictator
Gene Wilder - Willy Wonka & the Chocolate Factory
Jim Carrey - The Truman Show
Jack Nicholson - The Shining
Ian McKellen - The Lord of the Rings