One of the formulation of Kant's Categorical Imperative is that we should never treat humanity as a mere means to an end.
I wonder, then, whether this means that horror film directors are behaving unethically. After all, in a horror film, terrible things are made to happen to human beings, solely for the purpose of frightening/pleasing the audience. The human beings may be fictional, but it is nevertheless the fact that they are fictional *humans* that makes horror films effective (as opposed to a horror film where the victims are all robots). It seems to me that the humanity of the fictional characters is being used as a tool to manipulate the audience's emotions.
Does this fall under the umbrella of the humanity formulation of the Categorical Imperative? If not, why not? It certainly seems that it is the humanity of the victims (including their emotions, their aspirations, their mortality, their ability to suffer) that is key to the function of horror films.