Killers of the Flower Moon is a 2023 American epic Western crime drama film co-produced and directed by Martin Scorsese, who co-wrote the screenplay with Eric Roth. It is based on the 2017 book of the same name by David Grann. Set in 1920s Oklahoma, it focuses on a series of murders of Osage members and relations in the Osage Nation after oil was discovered on tribal land. The tribal members had retained mineral rights on their reservation, but a corrupt local political boss sought to steal the wealth.

Leonardo DiCaprio, Robert De Niro, and Lily Gladstone lead an ensemble cast, also including Jesse Plemons, Tantoo Cardinal, John Lithgow, and Brendan Fraser. It is the sixth feature film collaboration between Scorsese and DiCaprio, the tenth between Scorsese and De Niro, and the first between Scorsese and both actors overall (they previously all collaborated on the 2015 short film The Audition), and the eleventh and final between Scorsese and composer Robbie Robertson, who died two months before the film's release. The film is dedicated to Robertson.

Development began in March 2016 when Imperative Entertainment won the adaptation rights to the book. Scorsese and DiCaprio were attached to the film in 2017, with production expected to begin in early 2018. Following several pushbacks and delays due to the COVID-19 pandemic, production was scheduled to start in February 2021, with Apple Studios confirmed to finance and distribute the film alongside Paramount Pictures. Principal photography ultimately took place between April and October 2021 in Osage and Washington counties, Oklahoma. The film was produced by Scorsese's Sikelia Productions and DiCaprio's Appian Way Productions, with its $200–215 million budget reportedly the largest amount ever spent on a film shoot in Oklahoma.

Killers of the Flower Moon premiered at the 76th Cannes Film Festival on May 20, 2023. It was theatrically released in the United States on October 20, by Paramount Pictures, before streaming on Apple TV+ on January 12, 2024. The film grossed $158 million worldwide and received critical acclaim, with praise for Scorsese's direction, screenplay, production values, editing, cinematography, musical score, and cast performances, especially DiCaprio, Gladstone, and De Niro, although it received minor criticism for its runtime. It won Best Film at the National Board of Review and was named one of the top 10 films of 2023 by the American Film Institute. It was also nominated for ten Academy Awards (including Best Picture), seven Golden Globe Awards (including Best Motion Picture – Drama), nine British Academy Film Awards (including Best Film), and three SAG Awards. For her performance, Gladstone won the Golden Globe and Screen Actors Guild Award for Best Actress, as well as earned a nomination at the Academy Awards.