The Academy Awards (aka the Oscars) was created in 1927 as a kind of "super union", and only the elite of the industry were invited to join. Only members of the Academy of Motion Picture Arts and Sciences may nominate and vote for candidates for the Oscars. Here are the winners from 1940 through 1959. Also, see the winners from 1927 through 1939.

1940	1941
Best Picture	Best Picture
Rebecca	How Green Was My Valley
Best Director	Best Director
John Ford, The Grapes of Wrath	John Ford, How Green Was My Valley
Best Actor	Best Actor
James Stewart, The Philadelphia Story	Gary Cooper, Sergeant York
Best Actress	Best Actress
Ginger Rogers, Kitty Foyle	Joan Fontaine, Suspicion

1942	1943
Best Picture	Best Picture
Mrs. Miniver	Casablanca
Best Director	Best Director
William Wyler, Mrs. Miniver	Michael Curtiz, Casablanca
Best Actor	Best Actor
James Cagney, Yankee Doodle Dandy	Paul Lukas, Watch on the Rhine
Best Actress	Best Actress
Greer Garson, Mrs. Miniver	Jennifer Jones, The Song of Bernadette

1944	1945
Best Picture	Best Picture
Going My Way	The Lost Weekend
Best Director	Best Director
Leo McCarey, Going My Way	Billy Wilder, The Lost Weekend
Best Actor	Best Actor
Bing Crosby, Going My Way	Ray Milland, The Lost Weekend
Best Actress	Best Actress
Ingrid Bergman, Gaslight	Joan Crawford, Mildred Pierce

1946	1947
Best Picture	Best Picture
The Best Years of Our Lives	Gentleman's Agreement
Best Director	Best Director
William Wyler, The Best Years of Our Lives	Elia Kazan, Gentleman's Agreement
Best Actor	Best Actor
Fredric March, The Best Years of Our Lives	Ronald Colman, A Double Life
Best Actress	Best Actress
Olivia de Havilland, To Each His Own	Loretta Young, The Farmer's Wife

1948	1949
Best Picture	Best Picture
Hamlet	All The King's Men
Best Director	Best Director
John Huston, The Treasure of the Sierra Madre	Joseph L Mankiewicz, A Letter to Three Wives
Best Actor	Best Actor
Laurence Olivier, Hamlet	Broderick Crawford, All The King's Men
Best Actress	Best Actress
Jane Wyman, Johnny Belinda	Olivia de Havilland, The Heiress

1950	1951
Best Picture	Best Picture
All About Eve	An American in Paris
Best Director	Best Director
Joseph L Mankiewicz, All About Eve	George Stevens, A Place in the Sun
Best Actor	Best Actor
Jose Ferrer, Cyrano de Bergerac	Humphrey Bogart, The African Queen
Best Actress	Best Actress
Judy Holliday, Born Yesterday	Vivien Leigh, A Streetcar Named Desire

1952	1953
Best Picture	Best Picture
The Greatest Show on Earth	From Here to Eternity
Best Director	Best Director
John Ford, The Quiet Man	Fred Zimmerman, From Here to Eternity
Best Actor	Best Actor
Gary Cooper, High Noon	William Holden, Stalag 17
Best Actress	Best Actress
Shirley Booth, Come Back Little Sheba	Audrey Hepburn, Roman Holiday

1954	1955
Best Picture	Best Picture
On the Waterfront	Marty
Best Director	Best Director
Elia Kazan, On the Waterfront	Delbert Mann, Marty
Best Actor	Best Actor
Marlon Brando, On the Waterfront	Ernest Borgnine, Marty
Best Actress	Best Actress
Grace Kelly, The Country Girl	Anna Magnani, The Rose Tattoo

1956	1957
Best Picture	Best Picture
Around the World in 80 Days	The Bridge on the River Kwai
Best Director	Best Director
George Stevens, Giant	David Lean, The Bridge on the River Kwai
Best Actor	Best Actor
Yul Brynner, The King and I	Alec Guiness, The Bridge on the River Kwai
Best Actress	Best Actress
Ingrid Bergman, Anastasia	Joanne Woodward, The Three Faces of Eve

1958	1959
Best Picture	Best Picture
Gigi	Ben Hur
Best Director	Best Director
Vincente Minnelli, Gigi	William Wyler, Ben Hur
Best Actor	Best Actor
David Niven, Separate Tables	Charleton Heston, Ben Hur
Best Actress	Best Actress
Susan Hayward, I Want to Live	Simone Signoret, Room at the Top