Richard Matheson’s I Am Legend (1954), about a lone survivor in a postapocalyptic world inhabited by modern vampires, is the first major vampire novel of the 20th century and a direct response to Bram Stoker’s Dracula (1897). While replacing the supernaturalism of Stoker’s Gothic horror with science fiction elements, Matheson’s text is similarly concernedwith issues of racial ‘otherness’ centering around the liminal figure of the vampire and exhibits the same preoccupation with clean, unclean or mixed blood. This essay discusses the complex relationship between vampire fiction and discourses of race and monstrosity by analysing I Am Legend and its 2007 screen adaptation, whose manipulations of the original plot produced a film expressive of American attitudes towards science and religion after 9/11.