For which film did Matthew McConaughey win the Oscar for Best Actor?

Who won the Oscar for Best Actor for 'The Artist'? For which film did Jean Dujardin win the Oscar for Best Actor? Who won the Oscar for Best Actor for 'Lincoln'? Who won the Oscar for Best Actor for 'Dallas Buyers Club'? 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'? For which film did Leonardo DiCaprio win the Oscar for Best Actor?