How many movies have Buster Keaton and Roscoe 'Fatty' Arbuckle acted in together?

They have worked on 6 movies together! Their first movie together was The Round-Up (1920) while their highest rated movie together was Buster Keaton The Shorts Collection 1917-1923 (2016). They have not worked together since Buster Keaton The Shorts Collection 1917-1923 (2016). They are most known for their comedy films together.