Horror films seek to elicit negative emotional reactions from viewers by playing on primal fears. They often feature startling scenes involving the macabre, supernatural, or unknown. Common horror movie themes include things trying to kill people in or around haunted houses. Most have a killer/evil entity pursuing a single victim or group. Thriller films stimulate moods like anticipation, tension, and anxiety through suspense, uncertainty, and fast-paced action scenes usually involving a troublemaking main character.