Upon his return from battle in the previous film, the great warrior Hercules learns that his lover, Daianara, has lost her senses. Acording of the oracle Medea, Dianara's only hope is the Stone of Forgetfulness which lies deep in the realm of Hades. Hercules, with two companions, Theseus and Telemachus, embarks on a dangerous quest for the stone, while he is unaware that Dianara's guardian, King Lico, is the one responsible for her condition and plots to have the girl for himself as his bride upon her revival.
Unfortunately the movie Hercules in the Haunted World is not yet available on HBO Max.
| Production | Achille Piazzi | Producer |
| Writing | Mario Bava | Screenplay |
| Writing | Sandro Continenza | Screenplay |
| Writing | Duccio Tessari | Screenplay |
| Directing | Mario Bava | Director |
| Camera | Mario Bava | Director of Photography |
| Writing | Sandro Continenza | Story |
| Writing | Duccio Tessari | Story |
| Writing | Franco Prosperi | Story |
| Directing | Franco Prosperi | First Assistant Director |
| Directing | Bona Magrini | Script Supervisor |
| Art | Tony Sarzi-Braga | Assistant Production Design |
| Art | Giuseppe Ranieri | Assistant Production Design |
| Camera | Ubaldo Terzano | Camera Operator |
| Camera | Giuseppe Berta | Assistant Camera |
| Camera | Luciano Brebbia | Assistant Camera |
| Camera | Enrico Santelli | Still Photographer |
| Sound | Luigi Puri | Sound |
| Sound | Eugenio Fiori | Boom Operator |
| Sound | Adolfo Fabrizi | Sound Recordist |
| Costume & Make-Up | Silvano Giusti | Assistant Costume Designer |
| Costume & Make-Up | Renzo Francioni | Assistant Makeup Artist |
| Production | Giorgio Baldi | Unit Manager |
| Production | Dino Di Salvo | Production Secretary |
| Production | Giovanna Pellegrino | Production Secretary |
| Production | Alfredo Petri | Production Secretary |
| Production | Ernesto Poli | Administration |
| Costume & Make-Up | Maria Luisa Onorati | Seamstress |
| Costume & Make-Up | Valeria Sponsali | Seamstress |
| Editing | Lina Caterini | Assistant Editor |
| Sound | Tonino Cacciottolo | Foley Artist |
| Sound | Fausto Ancillai | Sound Mixer |
| Sound | Nino Renda | Sound Mixer |
| Camera | Joe D'Amato | Camera Operator |
| Writing | Mario Bava | Story |
| Writing | Franco Prosperi | Screenplay |
| Sound | Armando Trovajoli | Original Music Composer |
| Editing | Mario Serandrei | Editor |
| Art | Franco Lolli | Production Design |
| Costume & Make-Up | Mario Giorsi | Costume Design |
| Costume & Make-Up | Franco Palombi | Makeup Artist |
| Costume & Make-Up | Nicla Palombi | Hairstylist |
| Production | Danilo Marciani | Production Manager |
