I'm sorry to hear that nobody's told about Il Maestro, Stanley Kubrick.

1- Dr.Strangelove or: How i learned to stop worrying and love the bomb. (1963)
Stanley Kubrick as director, and Peter Sellers as the main actor as he was to play 4 characters, but could only played 3, due to an accident. A must see.




2-Paths of Glory. (1957)
From the same director, with Kirk Douglas.



3-Jaws. (1975)
Steven Spielberg's best movie.