Nonduality occupies a contested and generative position within the depth-psychology corpus, appearing variously as a metaphysical claim, a contemplative attainment, a psychological hazard, and a critique of spiritual narcissism. Masters provides the most sustained psychological interrogation, arguing that nondual awareness is neither a stage to be achieved nor a refuge from embodied life, but a living reality that must include rather than transcend the personal, the shadowy, and the egoic — and that its misappropriation fuels spiritual bypassing. Welwood and Cooper engage nonduality through the lens of Buddhist-psychotherapeutic dialogue, examining how Mahamudra, Dzogchen, and Dogen’s radical non-dualism reframe the relationship between self, thought, and awareness without collapsing the therapeutic dimension. Watts and Suzuki situate nonduality within classical Zen and Mādhyamika frameworks, showing its roots in the transcendence of conceptual pairs. Campbell and Zimmer approach it mythologically and comparatively. McGilchrist, by contrast, mounts a philosophically rigorous resistance to any simplistic monism, insisting that ‘All is One’ is only half a truth and that genuine nonduality must preserve rather than annul the tension of opposites. Aurobindo integrates the question into Vedantic ontology, where apparent dualities are aspects of a single self-differentiating Absolute. The convergence of these voices reveals nonduality as one of the corpus’s most theoretically dense and practically fraught terms.