- HD 1080
- Runtime: 75m.
- Status: Released
- 2
- Languages: en
- Country: Ireland, United States of America
- Director: Francis Ford Coppola
- Stars: William Campbell, Luana Anders, Bart Patton, Mary Mitchel, Patrick Magee
- keywords: heart attack, castle, pond, will, ceremony, psychotronic, proto-slasher
- Production_studio: The Filmgroup, Roger Corman Productions, American International Pictures
- Slogan: Are you afraid of death by drowning? Have you ever attempted suicide? Have you ever thought of committing murder?
- providers: Amazon Prime Video, fuboTV, Epix Amazon Channel, MGM Plus, Screambox, Fandor Amazon Channel, Screambox Amazon Channel, FilmBox+, Amazon Prime Video with Ads, Troma NOW
- The Dementia 13 is featured in the top rankings of 1963
- #28 in Top Thriller Movies of 1963
- #22 in Top Mystery Movies of 1963
- #23 in Top Horror Movies of 1963
A widow deceives her late husband's mother and brothers into thinking he's still alive when she attends the yearly memorial to his drowned sister, hoping to secure his inheritance, but her cunning is no match for the demented, axe-wielding thing roaming the grounds of the family's Irish estate.