20 Things You Didn't Know About Halloween (1978)
4. It Is Not A Bloodless Film
Especially when compared to the slasher films that followed it, Halloween is often regarded as being a cut above the rest (pun intended) because it does not show blood. This is an entire falsehood: there is plenty of blood in Halloween, but the mastery of the film is in distracting the audience's attention from it.
For example, when the six-year-old Michael Myers kills his sister, Judith (Sandy Johnson) in the film's opening sequence, the blood is clear to see, but the flashing butcher's knife in Michael's hand distracts the audience's attention from it.
Later, Loomis only just overlooks a garage worker who has been stabbed by the adult Michael and, when Laurie discovers the bodies of her friends in the Wallace household, Nancy Kyes's Annie Brackett has had her throat slashed, but the lighting used in the scene helps to maintain a sense of mystery around how she met her grisly end.
Again, given how bloody his previous directorial effort, Assault on Precinct 13 had been, Carpenter looked to Hitchcock's Psycho when he made Halloween to familiarise himself with how to show blood onscreen, whilst distracting the audience's attention from it.