There’s a ghost in this machine—it comes at night and it possesses us to celebrate the best unseen villains in horror-movie history. It surrounds us with the mist, it follows us to our final destination, where we live under the shadow of invisible threats. It is time to let the bird outta the box and list the ten films with the most memorable, malignant, largely non-physical threats. It might from person to person, smile at you in a mirror, or leave footprints in the snow, but it cannot be largely visible for most of the film.