Anger is present as a key criterion in five diagnoses within DSM-5: Intermittent Explosive Disorder, Oppositional Defiant Disorder, Disruptive Mood Dysregulation Disorder, Borderline Personality Disorder and Bipolar Disorder. This review amasses scientific literature demonstrating that within each of these disorders, anger is a central clinical feature that is highly prevalent and predictive of important outcomes. For each disorder, we also discuss the phenomenology and etiology of anger. Although models of anger have been quite distinct across these disorders, few empirical studies have truly tested whether anger stems from different etiological factors across these different conditions. We end with a discussion of transdiagnostic research that draws from cognitive psychology, affective science, and the neuroscience of anger, and that also fits with integrative approaches to treatment.