The depth-psychology corpus approaches ‘defense mechanism’ not as a single, settled concept but as a contested and layered term whose meaning shifts dramatically depending on the theoretical register in which it is deployed. In the classical Freudian lineage, adopted and extended by Yalom, defenses are psychic operations — some conscious, some unconscious — that evolve specifically to manage anxiety, and they constitute the very fabric of psychopathology: they purchase safety at the cost of growth and authentic experience. Kalsched radically deepens this by proposing archetypal defenses — operations of the primal Self that, like a misfiring immune system, attack parts of the personality mistaken for foreign invaders, producing self-destructive patterns in traumatized individuals. Berry, writing from an archetypal-Jungian position, challenges the Freudian reading further still: the defense, she argues, expresses the very content it ostensibly guards against, and thus carries within it the seeds of the individuating telos it appears to obstruct. The somatic and trauma traditions — Levine, Ogden, LeDoux — situate defenses primarily in the body and nervous system, as innate animal responses (freeze, fight, flight, feigned death) organized by phylogenetically ancient circuits. Mathieu introduces spiritual bypass as a specifically spiritual form of defense mechanism, adaptive or maladaptive depending on its underlying drive and outcome. Von Franz and Hillman gesture toward biological and typological analogues. Together these voices reveal defense mechanism as a site where psychoanalytic, Jungian, somatic, existential, and spiritual-developmental models collide most productively.