Hostility occupies a pivotal position across the depth-psychology corpus, functioning simultaneously as a clinical phenomenon, a psychodynamic mechanism, and a philosophico-ethical category. Freud establishes its foundational significance through the concept of ambivalence: unconscious hostility toward loved or venerated objects is universal, and its management through projection, taboo, and obsessive self-reproach defines a core axis of both neurotic and ‘primitive’ mental life. Fromm extends this line by identifying hostility directed against the self — internalized as conscience and duty — as a structural feature of modern character under capitalism and Calvinist moral culture, linking it to authoritarianism and the flight from freedom. Yalom brings hostility squarely into the clinical arena of group psychotherapy, tracking its sources (narcissistic injury, transference, sibling rivalry, prejudice) and its management as a therapeutic variable, while also documenting its role in intergroup dynamics and the emergence of prejudice. Konstan’s classical scholarship provides the conceptual archaeology of hostility’s Greek antecedents — distinguishing ekhthros (personal enmity, former friend turned foe) from polemioi (armed enemy) and contrasting hatred as a durable disposition from anger as a situational response to slight. Nussbaum and Nietzsche each situate hostility within ethical systems — the former connecting it to Lucretian schemes of fearful self-sufficiency, the latter to ressentiment. Together these strands reveal hostility not as a simple destructive impulse but as a structurally over-determined affect whose handling — repressed, projected, therapeutically worked through, or philosophically sublimated — is central to depth psychology’s project.