For which film did Leonardo DiCaprio win the Oscar for Best Actor?

For which film did Matthew McConaughey win the Oscar for Best Actor? Who won the Oscar for Best Actor for 'The Theory of Everything'? For which film did Eddie Redmayne win the Oscar for Best Actor? Who won the Oscar for Best Actor for 'The Revenant'? Who won the Oscar for Best Actor for 'Manchester by the Sea'? For which film did Casey Affleck win the Oscar for Best Actor? Who won the Oscar for Best Actor for 'Darkest Hour'? For which film did Gary Oldman win the Oscar for Best Actor?