How many movies have John Marley and Robert Duvall acted in together?

They have worked on 4 movies together! Their first movie together was Nightmare in the Sun (1965) while their highest rated movie together was The Godfather 1901–1959: The Complete Epic (1981). They have not worked together since The Godfather 1901–1959: The Complete Epic (1981). They are most known for their drama films together.