Citizen Kane is a 1941 American drama film directed by, produced by and starring Orson Welles and co-written by Welles and Herman J. Mankiewicz. It was Welles's first feature film.

Citizen Kane is frequently cited as the greatest film ever made. For 40 years (five decennial polls: 1962, 1972, 1982, 1992 and 2002), it stood at number one in the British Film Institute's Sight & Sound decennial poll of critics, and it topped the American Film Institute's 100 Years ... 100 Movies list in 1998, as well as its 2007 update. The film was nominated for Academy Awards in nine categories and it won for Best Writing (Original Screenplay) by Mankiewicz and Welles. Citizen Kane is praised for Gregg Toland's cinematography, Robert Wise's editing, Bernard Herrmann's score and its narrative structure, all of which have been considered innovative and precedent-setting.

The quasi-biographical film examines the life and legacy of Charles Foster Kane, played by Welles, a composite character based on American media barons William Randolph Hearst and Joseph Pulitzer, Chicago tycoons Samuel Insull and Harold McCormick, as well as aspects of the screenwriters' own lives. Upon its release, Hearst prohibited any mention of the film in his newspapers.

After the Broadway success of Welles's Mercury Theatre and the controversial 1938 radio broadcast "The War of the Worlds" on The Mercury Theatre on the Air, Welles was courted by Hollywood. He signed a contract with RKO Pictures in 1939. Although it was unusual for an untried director, he was given freedom to develop his own story, to use his own cast and crew, and to have final cut privilege. Following two abortive attempts to get a project off the ground, he wrote the screenplay for Citizen Kane with Herman J. Mankiewicz. Principal photography took place in 1940, the same year its innovative trailer was shown, and the film was released in 1941. Cecilia Ager, reviewing it in PM Magazine, wrote: “Seeing it, it’s as if you never really saw a movie before.”

Although it was a critical success, Citizen Kane failed to recoup its costs at the box office. The film faded from view after its release, but it returned to public attention when it was praised by French critics such as André Bazin and re-released in 1956. In 1958, the film was voted number nine on the prestigious Brussels 12 list at the 1958 World Expo. The Library of Congress selected Citizen Kane as an inductee of the 1989 inaugural group of 25 films for preservation in the United States National Film Registry for being "culturally, historically, or aesthetically significant".

Roger Ebert wrote of it: Its surface is as much fun as any movie ever made. Its depths surpass understanding. I have analyzed it a shot at a time with more than 30 groups, and together we have seen, I believe, pretty much everything that is there on the screen. The more clearly I can see its physical manifestation, the more I am stirred by its mystery.