“The oldest and strongest emotion of mankind is fear, and the oldest and strongest kind of fear is fear of the unknown.” — H. P. Lovecraft This statement was true when H. P. Lovecraft first wrote it at the beginning of the twentieth century, and it remains true at the beginning of the twenty-first century. The only thing that has changed is what is unknown. With each passing year, science, technology, and the march of time shine light into the craggy corners of the universe, making the fears of an earlier generation seem quaint. But this “light” creates its own shadows. The Best Horror of the Year, edited by Ellen Datlow, chronicles these shifting shadows. It is a catalog...