The paper takes as its starting point the category of the Other which has deeply marked the contemporary philosophy, although in very different ways. The red thread is the category of the Other in psychoanalysis, where already Freud spoke of the unconscious as “the other scene”, and Lacan emphatically proposed formulas like “the unconscious is the discourse of the Other”, “the desire is the desire of the Other” and spoke about women as “the Other sex”. The paper tries to provide some clarity in the various uses of this term in psychoanalysis. Finally one has to confront the fundamental antinomy that on the one hand the dimension of Otherness presents the basic terrain of all psychoanalytic concepts, and on the other hand the key thesis proposed by Lacan that “the Other doesn’t exist”. But if the Other doesn’t exist it doesn’t mean that it doesn’t produce effects, and this is the main difficulty in conceiving the Other. The paper tries to situate this problem in a wider philosophical context, reaching from the ancient atomism via Hegel to the contemporary philosophy.