"The Monstrumologist Series" is a young adult horror fiction series written by Rick Yancey. It follows the story of Will Henry, an orphaned boy who becomes an apprentice to Dr. Warthrop, a scientist dedicated to studying monsters. Set in the late 19th century, the series explores themes of fear, morality, and the nature of humanity through encounters with various mythical creatures. The series consists of four main books: "The Monstrumologist," "The Curse of the Wendigo," "The Isle of Blood," and "The Final Descent." Each installment delves deeper into the world of monsters, blending historical elements with thrilling narratives that challenge the characters' beliefs and survival instincts.