This chapter examines atypical, severe nonsuicidal self-injury (NSSI). The author proposes that atypical, severe NSSI be considered a different category of behavior, distinct from common, low-lethality NSSI. The author also proposes that atypical NSSI, despite being more severe, can also be differentiated from suicide attempts. In addition to presenting evidence for atypical, severe NSSI, the author describes a hierarchy of risk for this condition, as well as a sequential, multi-modal approach for intervention. Finally, case studies are presented to illustrate the condition as well as the assessment and treatment approach.