Orson Welles, 1941. The newspaper magnate Charles Foster Kane and the dying word 'Rosebud'. Deep focus, non-linear editing. Topped Sight & Sound's poll for fifty years.
From Wikipedia
Citizen Kane is a 1941 American drama film directed, produced by, and starring Orson Welles and co-written by Welles and Herman J. Mankiewicz. It was Welles's first feature film. 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, and Chicago tycoons Samuel Insull and Harold McCormick, as well as aspects of the screenwriters' own lives.