New York City's Theater District, sometimes spelled Theatre District and officially zoned as the "Theater Subdistrict", is an area and neighbourhood in Midtown Manhattan where most Broadway theatres are located, in addition to other theaters, movie theaters, restaurants, hotels, and other places of entertainment. It is bounded by West 40th Street on the south, West 54th Street on the north, Sixth Avenue on the east and Eighth Avenue on the west, and includes Times Square. The Great White Way is the name given to the section of Broadway which runs through the Theater District.

It also contains recording studios, record label offices, theatrical agencies, television studios, restaurants, movie theaters, Duffy Square, Shubert Alley, the Brill Building, and Madame Tussauds New York.

The City of New York defines the subdistrict for zoning purposes to extend from 40th Street to 57th Street and from Sixth Avenue to Eighth Avenue, with an additional area west of Eighth Avenue from 42nd Street to 45th Street. The Times Square Alliance, a business improvement district organization dedicated to improving the Theater District, defines the district as an irregularly shaped area within the bounding box of 40th Street, 6th Avenue, 53rd Street, and 9th Avenue. As of 2024, the Vivian Beaumont Theater (part of Lincoln Center) is the only Broadway-class theater not located in the Theater District.

The area known as Theatre Row is an area on 42nd Street from Ninth Avenue to Eleventh Avenue, which includes many off-Broadway and off-off-Broadway theaters.

In 1836, mayor Cornelius Lawrence opened 42nd Street to encourage the city's northern expansion, saying "move up town and enjoy the pure, clean air". The Theater District began attracting theaters and restaurants after the Metropolitan Opera House moved to West 39th Street and Broadway in 1883. Oscar Hammerstein I opened his Victoria Theatre on 42nd Street in 1899. Accessibility to the Theater District improved as electrified trolley lines started in 1899, followed by the opening of the New York City Subway's first line in 1904.

"The Great White Way" is a nickname for a section of Broadway in Midtown Manhattan that encompasses the Theater District. In 1880, Broadway between Union Square and Madison Square was illuminated by Brush arc lamps, making it among the first electrically lighted streets in the United States. By the 1890s, 23rd Street to 34th Street was so brightly illuminated by electrical advertising signs people began calling it "The Great White Way". As the theater district shifted uptown just before the turn of the century, the nickname stuck and became synonymous.

Over the years, the district has been referred to by New Yorkers as "the Rialto", "The Main Stem", and "Broadway". Around the turn of the 20th century, it was simply called "The Street".

By the 1970s, 42nd Street was seedy and run-down; X-rated movie houses, peep shows, and so-called grindhouses began to locate there. It was considered by some New Yorkers as a somewhat dangerous place to venture. However, in the 1990s the entire area was significantly revitalized by the city. Most of the adult theater businesses closed and an array of new theaters, multiplex movie houses, restaurants, and tourist attractions opened.