How many movies have Mario Bava and Paolo Ketoff collaborated on?

They have worked on 2 movies together! Their first movie together was Hercules Unchained (1959) while their highest rated movie together was Planet of the Vampires (1965). They have not worked together since Planet of the Vampires (1965).

Planet of the Vampires (1965)

Crew
Director
Crew
Sound Effects
Crew
Screenplay

Hercules Unchained (1959)

Crew
Director of Photography
Crew
Sound Mixer
Crew
Special Effects
Crew
Assistant Director