The Academy Award for Best Actress is one of the awards given to people working in the motion picture industry by the Academy of Motion Picture Arts and Sciences; the awards are voted on by other people within the industry. As is the customary practice in Wikipedia for listing Oscar results, the winner of the award for that year is listed first and in bold. The films below are listed with their production year, so for example the Oscar awarded in 2000 went to the Best Supporting Actress in 1999.
