Sergio Leone/Clint Eastwood 'Man with no name trilogy'. These flicks invented the spaghetti western.
Almost any Alfred Hitchcock, Akira Kurosawa or Mario Bava. Three of the world's greatest directors of all time.
Silent movies: Nosferatu & Metropolis.
Fritz Lang's "M"
Dario Argento's Deep Red & Suspiria. ( Italian director of several classic
1970s/1980s horror/suspense movies ).
Bruce Lee's 'Enter the Dragon' and the Shaw Brothers's '36th chamber of Shaolin'. These are two of the greatest kung fu movies ever made.
Peter Weir's "Picnic at hanging Rock". This is a classic film from the director of Witness, Truman Show & Master and Commander.