Fan Casting Can't Move While Being Watched in Sort by Tropes

A stock enemy that freezes and/or stops attacking when looked at, but will attack when line of sight is broken. It is fairly common in the Horror Genre, as it is a good source for Paranoia Fuel, especially when said mook tries to blend into the scenery. Also very common in Video Games, though it's much less likely to be played for horror if the thing moves whenever the player character looks away, even if the player can still see them from beyond the fourth wall.