Early childhood adversity can cause an imbalance in the autonomic function, which may in turn lead to the development of trauma-spectrum disorders and aggressive behavior later in life. In the present study, we investigated the complex associations between early adversity, heart rate variability (HRV), cluster B personality disorders, and self-reported aggressive behavior in a group of 50 male forensic inpatients (M age = 41.16; SD = 10.72). Structural Equation Modeling analysis revealed that patients with cluster B personality disorders were more likely to have adverse early childhood experiences and reduced sympathetic dominance in response to a threat than patients without cluster B personality disorders. In addition, HRV and cluster B personality disorders did not significantly mediate the association between early childhood adversity and self-reported aggressive behavior. These findings are important for clinical practice to facilitate specific treatment programs for those affected.