Ontology occupies a privileged and contested site within the depth-psychology corpus. The term arrives already charged with its Heideggerian freight: the fundamental inquiry into the meaning of Being, distinct from the merely ontical concern with particular entities. Heidegger’s sustained demolition of the Greek and Cartesian inheritance — wherein being collapses into presence, substance, or res extensa — sets the horizon against which later depth-psychological and hermeneutical writers position themselves. Hillman draws the term directly into clinical territory, arguing that psychotherapy requires what he calls ‘an ontology of analysis,’ a foundational account of what analysis is, not merely what it does. Ricoeur prosecutes the ontological question most systematically, asking whether a hermeneutics of selfhood can sustain an ontological commitment — whether ipseity, attestation, and narrative identity carry genuine being-claims or merely epistemological ones. He negotiates between analytic event-ontology (Davidson, Parfit) and the phenomenological tradition, seeking an ontology of act and potentiality that honours Aristotelian polysemy without collapsing into substantialism. Simondon introduces an ontology of individuation in which being is understood as pre-individual, processual, and phase-transitional rather than substantial. Thompson raises the question of ontological emergence in relation to biological mind. Across these voices, the central tension is between substance ontology and process or relational ontology, with depth psychology consistently favouring the latter.