Academy Award for Best Actress

The Academy Award for Best Actress is an award presented annually by the Academy of Motion Picture Arts and Sciences (AMPAS). It is given in honor of an actress who has delivered an outstanding performance in a leading role while working within the film industry. The award was traditionally presented by the previous year's Best Actor winner.

The 1st Academy Awards ceremony was held in 1929 with Janet Gaynor receiving the award for her roles in 7th Heaven, Street Angel, and Sunrise. Currently, nominees are determined by single transferable vote within the actors branch of AMPAS; winners are selected by a plurality vote from the entire eligible voting members of the Academy. In the first three years of the awards, actresses were nominated as the best in their categories. At that time, all of their work during the qualifying period (as many as three films, in some cases) was listed after the award. However, during the 3rd ceremony held in 1930, only one of those films was cited in each winner's final award, even though each of the acting winners had two films following their names on the ballots.

The following year, this unwieldy and confusing system was replaced by the current system in which an actress is nominated for a specific performance in a single film. Starting with the 9th ceremony held in 1937, the category was officially limited to five nominations per year. One actress has been nominated posthumously, Jeanne Eagels. Only three film characters have been nominated more than once in this category: Elizabeth I of England (twice by Cate Blanchett), Leslie Crosbie in The Letter, and Esther Blodgett in A Star Is Born. Seven women on the list have received an Honorary Academy Award for their acting; they are Greta Garbo, Barbara Stanwyck, Mary Pickford, Deborah Kerr, Gena Rowlands, Cicely Tyson and Sophia Loren.

Since its inception, the award has been given to 75 actresses. Katharine Hepburn has won the most awards in this category, with four Oscars. Meryl Streep, who has a total of 21 Oscar nominations (three wins), has been nominated in this category on 17 occasions, resulting in two awards. As of the 2018 ceremony, Frances McDormand is the most recent winner in this category for her role as Mildred Hayes in Three Billboards Outside Ebbing, Missouri.

Winners and nominees
In the following table, the years are listed as per Academy convention, and generally correspond to the year of film release in Los Angeles County; the ceremonies are always held the following year. For the first five ceremonies, the eligibility period spanned twelve months from August 1 to July 31. For the 6th ceremony held in 1934, the eligibility period lasted from August 1, 1932, to December 31, 1933. Since the 7th ceremony held in 1935, the period of eligibility became the full previous calendar year from January 1 to December 31.

Multiple wins and nominations
The following individuals received two or more Best Actress awards:

The following individuals received four or more Best Actress nominations: