How many movies have Shani Wallis and Steven Marlo acted in together?

They have worked on 3 movies together! Their first movie together was Terror in the Wax Museum (1973) while their highest rated movie together was Mayday at 40,000 Feet (1977). They have not worked together since Mayday at 40,000 Feet (1977). They are most known for their horror films together.