Gangs of New York is a 2002 American epic historical drama film directed by Martin Scorsese and written by Jay Cocks, Steven Zaillian, and Kenneth Lonergan, based on Herbert Asbury's 1928 book The Gangs of New York. The film stars Leonardo DiCaprio, Daniel Day-Lewis, and Cameron Diaz, along with Jim Broadbent, John C. Reilly, Henry Thomas, Stephen Graham, Eddie Marsan, Brendan Gleeson, and Liam Neeson in supporting roles. The film also marks the start of a collaboration between DiCaprio and Scorsese.

The film is set in 1863, when a long-running Catholic–Protestant feud erupts into violence, just as an Irish immigrant group is protesting the threat of conscription during the Civil War. Scorsese spent 20 years developing the project until Miramax Films acquired it in 1999. Principal photography took place in Cinecittà Studios in Rome, and Long Island City, New York City.

Gangs of New York was completed by 2001 but its release was delayed due to the September 11 attacks. The film was theatrically released in the United States on December 20, 2002, and grossed $193.8 million worldwide. It was met with generally positive reviews, and Day-Lewis's performance was highly acclaimed. It received 10 nominations at the 75th Academy Awards, including Best Picture, Best Director for Scorsese and Best Actor for Day-Lewis.