Z.P.G. (short for "Zero Population Growth") is a 1972 Danish-American dystopian science fiction film directed by Michael Campus and starring Oliver Reed and Geraldine Chaplin. It was inspired by the best-selling 1968 non-fiction book The Population Bomb, by Paul R. Ehrlich. The film concerns an overpopulated future Earth whose world government executes those who violate a 30-year ban on having children. Filmed in Denmark, the film is almost entirely set-bound featuring art direction designed to reflect a bleak, oppressive future.