Halloween is an American slasher media franchise that consists of thirteen films, as well as novels, comic books, a video game and other merchandise. The films primarily focus on Michael Myers, who was committed to a sanitarium as a child for the murder of his sister, Judith Myers.

His motivations for killing can be interpreted in several ways: Psychological Instability: Michael is depicted as having a severe mental illness. After murdering his sister at a young age, he is institutionalized, and his violent tendencies are exacerbated by a lack of treatment and understanding of his condition.