The Detective is a 1968 American neo-noir crime drama film starring Frank Sinatra. Directed by Gordon Douglas and produced by Aaron Rosenberg, it is based on the 1966 novel of the same name by Roderick Thorp.

Co-stars include Lee Remick, Jacqueline Bisset, Jack Klugman, William Windom, and Robert Duvall, with a script by Academy Award-winning screenwriter Abby Mann. The book's rights were owned by Robert Evans, who was to produce the film but never got a chance to when Evans was hired by Gulf+Western to run Paramount Pictures.

The Detective marked a move towards — and was billed as — a more "adult" approach to depicting the life and work of a police detective while confronting, for one of the first times in mainstream cinema, previously taboo subjects such as homosexuality. Here, the detective in question is Joe Leland, who is trying to juggle marital issues with a murder case that seemed to be open-and-shut at first but runs much deeper than he could have imagined.

The Detective was Sinatra's fourth collaboration with director Douglas, having worked together on Young at Heart (1954), Robin and the 7 Hoods (1964), Tony Rome (1967), and then later Lady in Cement (1968).