Warning: What follows is explicit. These movies (and their accompanying photos) are not chosen for their beauty, but rather for their primal power to shock. And why is that important? Sometimes, in the case of politics and sex, filmmakers can be liberators, leading a charge that elevates the medium’s significance. Elsewhere—especially in the case of violence—a movie can warn us of where we might be headed. These 50 entries are the extremes. We welcome your response.