Which actor won an Oscar for playing Arthur Fleck in 'Joker'?

In 'Kill Bill', who plays The Bride? Which actor won an Oscar for playing Hans Landa in 'Inglourious Basterds'? Which actor won an Oscar for playing Anton Chigurh in 'No Country for Old Men'? Which actor won an Oscar for playing the Joker in 'The Dark Knight'? 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 King George VI in 'The King's Speech'?