The Dexter TV show, much like the literary series it is closely adapted from, features detective hero Dexter Morgan who, though a blood-spatter analyst and killer hunter, is also a serial killer himself. Unlike other killers featured in fiction though, his murderous actions are specifically code-driven; he only pursues dangerous criminals who escape the law. It is because the show encourages readers to empathise with this somewhat unusual detective that the show attracted not only academic attention from television analysts, philosophers, psychologists, linguists and cultural studies specialists, but significant opposition from such groups as the US Parents Television Council as well. Regardless of whose ideologies it is that the show implies exactly, this article turns to direct viewer-derived data instead, in the form of selected internet forum messages over the first 5 episodes of the fifth series of the show (screened in the USA in the autumn of 2010). The critical linguistic analysis of this data uncovers the ways in which real viewers actually respond to serial killer-related ideologies with respect, for instance, to attitudes toward extreme crime and victim typology in US society. Through a discussion of specific message board strings from Showtime’s online Dexter forum, the article not only accounts for evidence with respect to the show’s implied ideologies, but more particularly investigates viewer reactions to them also.