This chapter considers the large group of books in which someone appropriates another person’s identity and traces a number of influences on such representations, including two famous historical cases of impersonation, those of the Tichborne claimant and of Anna Anderson, who claimed to be the Grand Duchess Anastasia. In some cases the detective is not who they seem to be (Albert Campion is not the real name of Margery Allingham’s detective, and nor is it the only one he uses); sometimes it is the villain who has assumed either a false name or a false nationality; sometimes it is a more sympathetic character who uses a name which is not their own, as when Raffles hides his real identity after his supposed death. Sometimes characters have allegorical identities, even if these are only temporary: Brat Farrar announces himself to Simon Ashby as ‘Retribution’, Miss Marple is labelled ‘Nemesis’ by Jason Rafiel. Sometimes there is double imposture, as in Julian Symons’ The Belting Inheritance, and it is not only the living who may be impostors; a recurrent question in Golden Age detective fiction is who is in the coffin. These books underline the difficult, contingent, and complex nature of the social ties which make us who we are.