Many critics have noted the presence of doubles, or counterparts, in Dickens’s work. These sets of counterparts, which most often consist of two, but sometimes of several, characters, fulfil various functions. While Dickens’s novels contain a wide variety of different types of counterpart sets, I have, in this thesis, however, only examined a specific sub-group of counterpart relationships. This sub-group is one in which the counterpart set consists of at least one good character and one bad character who are united by a complex relationship of mutual opposition and repulsion, and obsession and fascination. The light, or good character, is sometimes, but not always, the main protagonist of the novel. The dark, or evil counterpart, has destructive qualities which eventually lead to the death of someone in the novel. Frequently this negative character also poses a direct threat to his or her counterpart. These sets of counterparts are furthermore seen in connection with Dickens’s lifelong interest in crime and in particular the psychology of murder. The novels analysed are Oliver Twist (1837-9), Barnaby Rudge (1841), Bleak House (1852-53), Great Expectations (1860-61) and Our Mutual Friend (1864-65), as well as Dickens’s last and uncompleted work, The Mystery of Edwin Drood (1870). This selection is based on the following criteria: First, that these novels have among their characters at least one set of dark and light counterparts who are locked in a relationship of simultaneous opposition and attraction. Furthermore, a murder or an attempted murder is either committed by the bad character in this relationship, or takes place as a result of actions and influences that this character is responsible for; or, alternatively, there must be a strong basis to assume that a murder has taken place. The last criterion is that these novels were published over a period of more than thirty years and should therefore show changes in Dickens view during his writing career.My aim in this thesis has been fourfold. Firstly, to attempt to find out where Dickens stood in relation to the discourse on crime, and especially murder, in Victorian society, and also to find out if his view changed during the years and how this is reflected in the novels. Secondly, to analyse how he uses these counterpart sets to illustrate particular themes in his novels, and what these themes are. Thirdly, to find out if there are significant changes in the function of these counterparts, and further to attempt to draw some conclusions about the reasons for this. Finally, I have sketched the development of what I see as a major (even meta) theme in the novels examined. In addition to exploiting murder to illustrate other subjects, my finding is that Dickens was also exploring the mind of the murderer in depth, and this psychological probing and exploration can be traced in these novels.