In the first part of this paper, the author identifies some of the specific features of what Lacan calls the “other/Other”, concepts that could a priori lead to an analytical reflection on otherness. However, this is doubtful, as their multiple meanings designate very different, even contradictory, realities, the Other – with a capital “O” – being conceived first and foremost as the locus of the “discourse of the unconscious”, to the point of being synonymous with the latter. Secondly, the author suggests possible links between the shadow cast by this Other in the light of what we know of Lacan's childhood history, and also with some of his concepts – from the paranoia of self-punishment to the mirror stage, from the “discourse of the unconscious” to the strings of the Borromean knots – all of which evoke, directly or indirectly, this “other/Other”.