The October Man is a 1947 mystery film/film noir starring John Mills and Joan Greenwood, written by novelist Eric Ambler, who also produced. A man is suspected of murder, and the lingering effects of a brain injury he sustained in an earlier accident, as well as an intensive police investigation, make him begin to doubt whether he is innocent.

Joan Mary Waller Greenwood was an English actress. Her husky voice, coupled with her slow, precise elocution, was her trademark. She played Sibella in the 1949 film Kind Hearts and Coronets, and also appeared in The Man in the White Suit (1951), Young Wives' Tale (1951), The Importance of Being Earnest (1952), Stage Struck (1958), Tom Jones (1963) and Little Dorrit (1987).