Dr. Henry Armitage, an expert in the occult, goes to the old Whateley manor in Dunwich looking for Nancy Wagner, a student who went missing the previous night. He is turned away by Wilbur, the family's insidious heir, who has plans for the young girl. But Armitage won't be deterred. Through conversations with the locals, he soon unearths the Whateleys' darkest secret — as well as a great evil.
Unfortunately the movie The Dunwich Horror is not yet available on HBO Max.
| Writing | Curtis Hanson | Screenplay |
| Directing | Daniel Haller | Director |
| Writing | Ronald Silkosky | Screenplay |
| Writing | Henry Rosenbaum | Screenplay |
| Crew | Roger George | Special Effects |
| Production | Roger Corman | Executive Producer |
| Production | Samuel Z. Arkoff | Producer |
| Production | James H. Nicholson | Producer |
| Art | Raymond Boltz Jr. | Set Decoration |
| Art | Paul Sylos | Art Direction |
| Editing | Christopher Holmes | Editor |
| Crew | Richard C. Glouner | Cinematography |
| Writing | H.P. Lovecraft | Novel |
| Costume & Make-Up | Jack Obringer | Makeup Artist |
| Production | Jack Bohrer | Producer |
| Production | Norman T. Herman | Production Executive |
| Production | Jack Bohrer | Production Manager |
| Camera | Richard C. Glouner | Director of Photography |
| Art | Sandy Dvore | Title Designer |
| Sound | Al Simms | Music Supervisor |
| Directing | Lew Borzage | Assistant Director |
| Camera | Richard Wimpy | Camera Operator |
| Camera | Gene A. Talvin | Assistant Camera |
| Lighting | Jack Spicer | Gaffer |
| Camera | Charles Hannawalt | Key Grip |
| Camera | Richard King Sr. | Best Boy Grip |
| Sound | Charles T. Knight | Sound Mixer |
| Directing | Harry Harvey Jr. | Script Supervisor |
| Costume & Make-Up | Richard Bruno | Wardrobe Master |
| Costume & Make-Up | Faith Schmehr | Hairdresser |
| Art | C. Randall Berkeley | Property Master |
| Production | Tamara Asseyev | Production Assistant |
| Sound | Les Baxter | Original Music Composer |
