For which film did Jean Dujardin win the Oscar for Best Actor?

For which film did Jeff Bridges win the Oscar for Best Actor? Who won the Oscar for Best Actor for 'The King's Speech'? For which film did Colin Firth win the Oscar for Best Actor? Who won the Oscar for Best Actor for 'The Artist'? Who won the Oscar for Best Actor for 'Lincoln'? Who won the Oscar for Best Actor for 'Dallas Buyers Club'? For which film did Matthew McConaughey win the Oscar for Best Actor? Who won the Oscar for Best Actor for 'The Theory of Everything'?