Paranormal romance is a subgenre of both  romantic fiction and speculative fiction. Paranormal romance focuses on romantic love and includes elements beyond the range of scientific explanation, blending together themes from the speculative fiction genres of fantasy, science fiction, and horror. Paranormal romance may range from traditional category romances, such as those published by Harlequin Mills & Boon, with a paranormal setting to stories where the main emphasis is on a science fiction or fantasy-based plot with a romantic subplot included. Common hallmarks are romantic relationships between humans and vampires, shapeshifters, ghosts, and other entities of a fantastic or otherworldly nature.