This question involves making judgments and decisions about what is appropriate for a Christian to read. We all face this question regarding many facets of life, including the kind of music we listen to, the movies we watch and even the places we choose to go.
Everyone has to make his or her determination based on some fundamental principles. It would not be wise to simply say that since many people feel it is OK to read a certain fictional novel, then any fictional novel is acceptable. Everything has to be evaluated based on its own content and merit.
A person needs to ask what impact reading this book or seeing this movie is going to have. Some types of novels, movies, TV programs, etc., can be very emotionally upsetting and harmful to the mind. They can leave lasting, negative images and also begin to impact our sense of right and wrong.
We must be careful about what we allow into our minds. God does not expect us to avoid all forms of entertainment, but we are to consider if the experience has any redeeming value and what detrimental effects it may have on us, and then choose wisely.
To answer the question specifically, we recommend avoiding novels involving the dead, vampires and werewolves. These dark themes and fantasies are often rooted in satanic concepts and are not uplifting or educational. Because we might attend an occasional movie or read other fictional novels, it does not mean every type of reading material is healthy. Some who have delved heavily into this type of literature have ended up disturbed mentally.