One of the more familiar of the director's motifs, the double has received a fair amount of attention in the Hitchcock literature. Its prominence in Hitchcock's work is not surprising: not only was it a feature of some of the writers whom he admired – Edgar Allan Poe; E.T.A. Hoffmann – it was also found extensively in the German Expressionist cinema of the 1910s and 1920s which influenced him so strongly. Both these traditions are examined in Otto Rank's seminal psychoanalytical study of the double Der Doppelgänger (1914), and Rank's discussion in turn influenced Freud. (See Rank 1971, which includes a publication history of Rank's German articles on the subject; Freud's incorporation of Rank's ideas are in his essay ‘The Uncanny’, Freud 1919/1985: 356-58.) Although the range of doubles in Hitchcock is rather wider than those Rank considers, the latter's analysis is nevertheless extremely useful.

Rank begins his study with a detailed examination of DER STUDENT VON PRAG (Stellan Rye, 1913). In this film, and in Rank's main literary example, Dostoyevsky's The Double (1846), the double looks exactly like the hero but has an independent identity. Apart from the TV episode ‘The Case of Mr Pelham’ (1955), which is clearly modelled on Dostoyevsky's novella (➢ APPENDIX I), Hitchcock's doubles do not possess this uncanny resemblance to the protagonist and may even be of a different gender. Nevertheless, as in Rank's main examples, the connection between protagonist and double is usually psychological, with the double functioning as a sort of alter ego who typically carries out the protagonist's repressed or disavowed desires (in Jungian terms, his/her shadow).

In the British films, the motif of the double is in fact relatively rare. It applies to The Lodger, in that the Avenger may be seen as the Lodger's murderous alter ego (➢ GUILT AND CONFESSION). It might have been present in DOWNHILL, in that the offence for which the public school hero is blamed (getting a local girl pregnant) is committed by his best friend with the hero's connivance: the hero could have secretly wanted the sex. However, the Novello subtext (the registering, in his films, of his gayness) quite spectacularly undermines this (➢ HOMOSEXUALITY).