The term ‘Third’ occupies a remarkable range of registers across the depth-psychological corpus, from clinical structure to cosmological symbolism. Thomas Ogden’s formulation of the ‘analytic third’ — the co-created intersubjective field jointly produced by analyst and analysand — stands as one of the most influential technical elaborations, framing the therapeutic dyad as inevitably generating a third subject whose unconscious life must be tracked alongside the individual subjectivities it encompasses. James Hillman approaches the third from an Erotics of soul-making: triangulation is not a moral failure but a structural necessity of psychic creativity, so imperative that even the most exclusive dyad will imagine a third into existence. Esther Perel, writing from the relational tradition, situates the third as the shadow presence haunting every couple — the embodied or fantasised other who defines the boundary of desire and sustains erotic tension. Jung and his interpreters (Edinger, von Franz) read the third through number symbolism: the triad marks the dialectical movement of thesis-antithesis-synthesis, the emergence of ego consciousness from undifferentiated wholeness, and the trinitarian archetype common to theology, alchemy, and mythology. Giegerich dissents sharply, warning that positing a neutralising Third between opposites is an imaginistic evasion of genuine dialectical movement. The term thus sits at the intersection of technique, eros, individuation, and symbolic numerology, with significant tensions about whether the third resolves, evades, or generates psychic complexity.