The term ‘Apollonian’ occupies a structurally pivotal position in the depth-psychology corpus, functioning simultaneously as mythological descriptor, aesthetic category, and psychological principle. Its primary theorist remains Nietzsche, whose Birth of Tragedy establishes the Apollonian as the principle of luminous individuation, formal beauty, and dream-semblance standing in constitutive tension with Dionysian dissolution. Walter F. Otto translates this into phenomenological theology, reading Apollo’s ‘sharp clarity,’ distance, and will toward order as cosmologically grounded rather than merely conceptual. The corpus reveals a persistent tension between those who treat the Apollonian as a genuine, irreducible divine force — Otto, Kerenyi, Harrison — and those who deploy it instrumentally as a cultural diagnostic. Hillman employs the term critically, identifying ‘civilized’ Western culture as Apollonian in its valorization of ego-luminosity at the expense of imagination’s night-world, while Miller demonstrates, through the Oresteia, that the neglect of Apollo is as catastrophic as the neglect of the Furies. The Apollonian’s relationship to Dionysus is the corpus’s central drama: at Delphi, as Otto shows, the two gods shared festival time and temple pediment alike, suggesting not simple opposition but what Nietzsche called ‘reconciliation.’ Kerenyi and Burkert ground the term historically in initiation rites, the ephebic institution, and solar cult, complicating any purely philosophical appropriation.