A devote of the horror genre, Paul Tremblay considers A Head Full of Ghosts to be an homage to both William Peter Blatty’s novel The Exorcist (1971) and the 1973 film of the same title, directed by William Friedkin. He also integrates elements from other classic and modern horror films and series.

The Exorcist follows psychologist and Catholic priest Father Peter Karras as he participates in his first exorcism, that of an adolescent girl named Regan. Father Karras is approached by Regan’s mother because of his dual expertise in mental health and religion. Elements that appear in both A Head Full of Ghosts and The Exorcist include: a girl who is believed to be possessed speaks in several distinct voices and appears to have preternatural knowledge; the challenging, taunting, and tormenting of a priest; vomiting; violence; crawling around and other awkward movement patterns; frigid air permeating the room when an evil entity is present; graphic displays of masturbation; blasphemy; and murder. Blatty based The Exorcist on the true story of an exorcism, changing his main character to a young girl; his novel is purported to be based in or represent fact.

Another famous horror event and accompanying media frenzy surround the murders of the DeFeo family of Long Island, New York, and the experiences that the subsequent owners claimed occurred in the home where the killings occurred.