Michael Myers

Michael Myers was a chilling but still very human sociopath, a carrier of pure evil before he became an incarnation of mysterious, ancient power that was even sought after by a Religion of Evil, etc. Notably, his powers were inexplicable in the first movie, attributed to what was behind his eyes being "pure evil" by Doctor Loomis and the Boogeyman by Laurie Strode. Later ideas would be that he had a psychic connection to his niece Jamie and was tied to a Samhain-worshiping cult. Most of these were retconned away by Halloween (2018).

Example of:
Our Slashers Are Different