David Jonathan Heyman is a British film producer and the founder of Heyday Films. Heyman is best known as the producer of all eight installments of the Harry Potter film series, which are based on a series of popular fantasy novels of the same name by author J. K. Rowling. He then produced all three installments of its spin-off prequel series, Fantastic Beasts. His work makes him the second-most commercially successful producer of all time.