For which film did Halle Berry win the Oscar for Best Actress?

Who won the Oscar for Best Actress for 'Boys Don't Cry'? Who won the Oscar for Best Actress for 'Erin Brockovich'? For which film did Julia Roberts win the Oscar for Best Actress? Who won the Oscar for Best Actress for 'Monster's Ball'? Who won the Oscar for Best Actress for 'The Hours'? For which film did Nicole Kidman win the Oscar for Best Actress? Who won the Oscar for Best Actress for 'Monster'? For which film did Charlize Theron win the Oscar for Best Actress?