How many movies have Joe May and Paul Leni collaborated on?

They have worked on 6 movies together! Their first movie together was Stuart Webbs: The Man in the Cellar (1914) while their highest rated movie together was Ein Ausgestoßener, 2. Teil: Der ewige Friede (1915). They have not worked together since Der Farmer aus Texas (1925). They are most known for their drama films together.