Monsters represent some of human beings'' most intricate nightmares and fears, being rather recurrent figures in literature and cinema. By analyzing occurrences of monstrosity in two nineteenth-century novels, namely Oscar Wilde''s The Picture of Dorian Gray and Émile Zola''s Germinal, this book attempts to understand the significance of monstrosity within the context of each novel and to connect the presence of the monster in these works with the historical moment each society was experiencing. In order to achieve that, a theoretical discussion about the concepts of monstrosity is carried out, as well as a detailed literary analysis of each novel. As a conclusion, the comparison of the two novels points at three monstrous interpretations common to both: the monster as a transgression, as the result of a cultural crisis, and as a metaphor for evil. Finally, the presence of monstrosity in literature is explained according to the social and cultural circumstances of each country, ultimately demonstrating the global importance of literature in the understanding of culture as a whole.