The Doppelganger — the double, the spectral second self — occupies a distinctive and revealing position within the depth-psychology corpus. Otto Rank, who produced the foundational psychoanalytic study of the phenomenon (Imago, 1914), locates the double within the archaic psychology of the soul: the primitive belief in a bodily second self that survives death, traceable from the Egyptian Ka through South Slavic folk belief. For Rank, the Doppelganger is not merely a literary trope but an expression of the immortality wish, a projection of the soul-concept outward onto a phantasmatic double. Walter Burkert, engaging classical scholarship, registers the scholarly debate over whether Rohde’s reading of the Homeric psyche as a Doppelganger — a second ego — is defensible, finding it decisively refuted by subsequent philology. James Hillman reclaims the term from both folklore and pathology, deploying it within his acorn theory to name the irreducible duality of the genius and the person: the daimon-self and the biographical self coexisting in productive tension. Hillman reads nicknaming as a folk recognition of this duality, preserving the truth of the genius-name alongside the civil name. Together these voices reveal the Doppelganger as a node where soul-theory, immortality belief, literary imagination, and the psychology of vocation converge — a term whose range exceeds any single disciplinary framing.