How many movies have George R. Groves Jr. and Richard N. Gladstein collaborated on?

They have worked on 3 movies together! Their first movie together was Silent Night, Deadly Night 3: Better Watch Out! (1989) while their highest rated movie together was Silent Night, Deadly Night 5: The Toy Maker (1991). They have not worked together since Silent Night, Deadly Night 5: The Toy Maker (1991). They are most known for their horror films together.