From the screenplay stage and all the way through to production, The Dark (1979)'s antagonist was an abused, autistic child who had been locked in an attic for his entire life. In the original script, his house burned down, allowing him to escape and take vengeance on the outside world. Toward the end of the shoot, the film's producers decided to capitalize on the success of Alien: Das unheimliche Wesen aus einer fremden Welt (1979) and demanded extensive re-shoots to change the killer into an extra-terrestrial.
Cameo: Casey Kasem, radio host of American Top 40 and voice over actor for several popular cartoons, including the voice of Shaggy on Scooby Doo, as a pathologist.
Star William Devane came aboard The Dark in the hopes of working with Tobe Hooper, but Hooper (Eaten Alive, Texas Chainsaw Massacre) was let go from the project for falling way behind schedule after only three days. But new director John Cardos assured Devane he would be able to play his character as he saw fit.
Conflicting descriptions of who or what the killer is before the infamous reshoots have persisted for years, with some versions saying the killer was an escaped, autistic adult who had been abused since childhood. However, in the novelization of the film based on the original screenplay, the killer is a zombie-like being, most likely the resurrected cannibal madman Harmon Quade who was captured and lynched exactly 100 years ago to the day of the first killing in the film. Some of these descriptions made it into the theatrical cut of the film, such as the dead skin under the fingernails of the victims and the newspaper headlines stating "The mangler is a zombie". The appearance of the creature in the film matches exactly the description of zombie Harmon Quade (grey, rotted face with red sores and matted hair) in the novel. How and why Harmon Quade was resurrected is never explained.