For which film did Gary Oldman win the Oscar for Best Actor?

For which film did Leonardo DiCaprio win the Oscar for Best Actor? 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'? Who won the Oscar for Best Actor for 'Bohemian Rhapsody'? For which film did Rami Malek win the Oscar for Best Actor? Who won the Oscar for Best Actor for 'Joker'? For which film did Joaquin Phoenix win the Oscar for Best Actor?