Novels[]
- 1966 – Twinkle, Twinkle, "Killer" Kane
- 1971 – The Exorcist
- 1978 – The Ninth Configuration
- 1983 – Legion
- 1996 – Demons Five, Exorcists Nothing : A Fable
- 2010 – Dimiter
Novellas[]
- 1999 – Elsewhere
Novelettes[]
- 1965 – I, Billy Shakespeare!
- 2014 – Faith
Short Stories[]
- 2009 – Terry and the Werewolf
- 2014 – Hell Hospital