Night of the Living Dead (1968)
Director George A. Romero’s Night of the Living Dead and its subsequent installments, far from being pioneers of the genre, were the foundation of the zombie phenomenon as we know it today—and made people ponder the chances of an undead pandemic. It’s scientifically impossible to fall victim to reanimated corpses, but a parasite known as Toxoplasma gondii can possibly turn millions into shuffling hordes of the mindless and bloodthirsty. The scary part? T. gondii is already within half of the human population, sometimes affecting the brain in nearly the same manner as schizophrenia (now imagine that on a global scale).