The Academy Award for Best Original Screenplay is the Academy Award (also known as an Oscar) for the best screenplay not based upon previously published material. It was created in 1940 as a separate writing award from the Academy Award for Best Story. Beginning with the Oscars for 1957, the two categories were combined to honor only the screenplay.

See also the Academy Award for Best Adapted Screenplay, a similar award for screenplays that are adaptations of pre-existing material.

Screenplays are eligible if they are not based on "previously published material". The Writer's Branch of the academy determines if a screenplay is adapted or original, based on possible sources in question, interviews given about the film and the film's publicity materials, and sometimes places screenplays in a different category than the Writers Guild of America. For the 75th Academy Awards, Gangs of New York was nominated as an original screenplay despite being based on the book The Gangs of New York because the writers based the film on the book's historical research but largely invented the characters and plot.^[1] For the 89th Academy Awards, Moonlight was campaigned as an original screenplay, being based on an unpublished play, but was ultimately placed in the adapted screenplay category, which it won.^[2] Similarly, Whiplash was considered an adapted screenplay at the 87th Academy Awards despite being written as an original screenplay because a scene from the script was produced as a proof-of-concept short film. However, 2008's Frozen River, which similarly had a proof-of-concept short film screened at film festivals, was nominated as an original screenplay.^[3]

Woody Allen has the most nominations in this category with 16, and the most awards with 3 (for Annie Hall (1977), Hannah and Her Sisters (1986), and Midnight in Paris (2011)). Paddy Chayefsky and Billy Wilder have also won three screenwriting Oscars: Chayefsky won two for Original Screenplay (The Hospital and Network) and one for Adapted Screenplay (Marty), while Wilder won one for Adapted Screenplay (The Lost Weekend, shared with Charles Brackett), and two for Original Screenplay (Sunset Boulevard, shared with Brackett and D. M. Marshman Jr., and The Apartment, shared with I. A. L. Diamond)

Woody Allen also holds the record as the oldest winner (76) for Midnight in Paris.^[4] Ben Affleck is the youngest winner (25) for Good Will Hunting, co-written with Matt Damon (27).

Richard Schweizer was the first to win for a foreign-language film, Marie-Louise. Other winners for a non-English screenplay include Albert Lamorisse, Pietro Germi, Claude Lelouch, Pedro Almodóvar, Bong Joon-ho, Han Jin-won, Justine Triet and Arthur Harari. Lamorisse is additionally the only person to win or even be nominated for Best Original Screenplay for a short film (The Red Balloon, 1956).^[5]

Frances Marion (The Big House) was the first woman to win for her original script, although she won Best Writing, which then included both original and adapted screenplays before a separate award for Best Original Screenplay was introduced. Muriel Box (The Seventh Veil) was the first woman to win in this category; she shared the award with her husband, Sydney Box. They are also the first of two married couples to win in this category; Earl W. Wallace and Pamela Wallace (Witness) are the others.

In 1996, Joel Coen and Ethan Coen became the only siblings to win in this category (for Fargo).^[6] Francis Ford Coppola (Patton, 1970) ^[7] and Sofia Coppola (Lost in Translation, 2003) are the only father-daughter pair to win.^[8]

Preston Sturges was nominated for two different films in the same year (1944): Hail the Conquering Hero and The Miracle of Morgan's Creek. Oliver Stone achieved the same distinction in 1986, for Platoon and Salvador. Maurice Richlin and Stanley Shapiro were nominated in 1959 for both Operation Petticoat and Pillow Talk and won for the latter.

Jordan Peele became the first and only African-American to win in this category for 2017's Get Out.^[9]

Bong Joon-ho and Han Jin-won became the first Asian writers to win either Screenplay award, for 2019's Parasite.^[10][11] This was also the most recent of 10 occasions when Oscars in this category have been awarded to writers for both screenplay AND story on one film (sometimes they have been completely different, and sometimes the credited screenplay author also contributed to the story alongside at least one other credited scribe).

Winners are listed first in the colored row and denoted by double dagger (‡), followed by the other nominees.

• Academy Award for Best Story
• Golden Globe Award for Best Screenplay
• BAFTA Award for Best Original Screenplay
• Independent Spirit Award for Best Screenplay
• Critics' Choice Movie Award for Best Screenplay
• List of Big Five Academy Award winners and nominees
• Writers Guild of America Award for Best Original Screenplay