Who won the Oscar for Best Actor for 'Joker'?

Who won the Oscar for Best Actor for 'Darkest Hour'? For which film did Gary Oldman win the Oscar for Best Actor? Who won the Oscar for Best Actor for 'Bohemian Rhapsody'? For which film did Rami Malek win the Oscar for Best Actor? For which film did Joaquin Phoenix win the Oscar for Best Actor? Who won the Oscar for Best Actor for 'The Father'? Who won the Oscar for Best Actor for 'King Richard'? For which film did Will Smith win the Oscar for Best Actor?