Background: Evidence suggests the relationship between personality disorder (PD) and violence in offenders might be clarified by considering subgroups of PD offenders defined by patterns of PD comorbidity. Aim: to identify patterns of PD comorbidity associated with severe violence, defined by its severity, quantity and age of onset (Violence Index: VI) in a forensic sample of 100 PD offenders. Methods: Correlations were first computed between VI and a range of personality and criminological variables; next, patients with antisocial/borderline comorbidity were compared with other PD patients; finally, regression analysis was conducted to identify unique predictors of VI. Results: The antisocial deviance factor of psychopathy and antisocial/borderline comorbidity were each significantly and independently associated with severe violence. Patients showing both a high psychopathy score and antisocial/borderline comorbidity had a significantly greater VI than those without these characteristics. Conclusion: PD patients with high psychopathy co-occurring with borderline and antisocial PDs show a criminal profile characterised by a high degree of serious violence.