Which actor won an Oscar for playing King George VI in 'The King's Speech'?

Which actor won an Oscar for playing Arthur Fleck in 'Joker'? Which actor won an Oscar for playing J. Robert Oppenheimer? Which actor won an Oscar for playing Freddie Mercury in 'Bohemian Rhapsody'? Which actor won an Oscar for playing Abraham Lincoln in 'Lincoln' (2012)? Which actor won an Oscar for playing Ray Charles in 'Ray'? Which actor won an Oscar for playing Idi Amin in 'The Last King of Scotland'? Which actor won an Oscar for playing Winston Churchill in 'Darkest Hour'? Which actress won an Oscar for playing Queen Elizabeth II in 'The Queen'?