The Hills Have Eyes (1977)
The Hills Have Eyes is the late Wes Craven's third film (right behind something I've never heard of called The Fireworks Woman) from his masterful, groundbreaking first film, The Last House on the Left (1972), a film with social commentary and subtext a mile long, but one generally derided or even hated as being a misogynistic and sickening mess. (It's a whole helluva lot better and deeper than that, I can assure you, and I've got a whole essay about that you can read here: "The Castle and Krug".) Craven's most famous film is, of course, A Nightmare on Elm Street, and its resultant sequels and spin-offs and remakes, etc. He was a horror legend in Hollywood, and his brand was sterling when he tragically passed on.