On the Twentieth Century, was a Broadway musical with book and lyrics by Betty Comden and Adolph Green, and music by Cy Coleman, directed by Hal Prince. It opened in 1978 and starred Imogene Coca, John Cullum, Madeline Kahn and Kevin Kline. (Miss Kahn left the production fairly early in its run; her understudy, Judy Kaye, who had already gone on for her many times, took over the role and launched her own starring career.)

It was an adapation of a story first presented in Charles Bruce Millholland's play Napoleon of Broadway, based on his experiences working for the theater producer David Belasco. This was adapted by Ben Hecht and Charles MacArthur as the play Twentieth Century, which was produced and directed on Broadway in 1932 by George Abbott.

The plot, a screwball comedy, features an egomaniacal Broadway producer who makes a shopgirl into a star, then tries to win her back after she abandons him. Most of the action takes place aboard the New York City-Chicago train known as The Twentieth Century Limited.

The play was adapted by Hecht and MacArthur (credited) and by Gene Fowler and Preston Sturges (uncredited) for Howard Hawks's 1934 film, Twentieth Century, which starred John Barrymore and Carole Lombard.