Toward the Unknown, originally called Flight Test Center and titled Brink of Hell in its UK release, is a 1956 American aviation film about the dawn of supersonic flight filmed on location at Edwards Air Force Base. Starring William Holden, Lloyd Nolan and Virginia Leith, the film features the screen debut of James Garner.

Toward the Unknown was directed by Mervyn LeRoy and written by Beirne Lay, Jr. who had also penned the novel and screenplay for Twelve O'Clock High (1949), and later screenplays for Above and Beyond (1952) and Strategic Air Command (1955). The film's title is derived from the motto of the Air Force Flight Test Center, Ad Inexplorata.