The black dog occupies a pivotal position across the depth-psychology corpus, functioning simultaneously as chthonic symbol, dream-image, alchemical emblem, and mythological cipher. Jung’s seminar discussions treat the black dog as a direct psychic descendant of the underworld guardian Cerberus — a figure that embodies the dark, devouring aspect of the unconscious demanding acknowledgment and ritual appeasement. In the alchemical register, Hillman locates the ‘alchemical blue dog’ within the nigredo, linking canine symbolism to depression, the Saturnian grinding of the opus, and states of soul resistant to transformation. Edinger reads the black dog’s mythological lineage through Hecate’s attribute, revealing its initiatory function: the animal that extracts what is buried from the earth, mediating between the living and the dead. Von Franz situates dogs — including their dark variants — as mankind’s most intimate psychic mirror, representing the alter ego and instinctual contact. Jung’s dream-seminar material goes further, arguing that the black dog that emerges from death’s transformation signals a chthonic life-force risen from the lowest depths of the psyche, connected to sacrifice, corporality, and renewal. The term thus condenses the corpus’s major tensions around shadow, nigredo, instinct, and the underworld: between the dog as loyal companion and as devouring pursuer, between symbolic opening and literal danger.