David Holzman's Diary

David Holzman's Diary is a 1967 American mockumentary, or work of metacinema, directed by James McBride and starring L. M. Kit Carson. A feature-length film made on a tiny budget over several days, it is a work of experimental fiction presented as an autobiographical documentary. "A self-portrait by a fictional character in a real place—New York's Upper West Side," the film comments on the title character's personality and life as well as on documentary filmmaking and the medium of cinema more generally. In 1991, David Holzman's Diary was included in the annual selection of 25 motion pictures added to the National Film Registry of the Library of Congress, being deemed "culturally, historically, or aesthetically significant" and recommended for preservation.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.