Narcissistic Personality Disorder (NPD) is a personality disorder that involves a long-term pattern of abnormal behavior characterized by exaggerated feelings of self-importance, an excessive need for admiration, and a lack of understanding of others' feelings. Sadism is an additional factor observed in the most severe type of NPD, malignant narcissism. At the psychological level NPD is usually diagnosed or studied using some type of self-report diagnostic instrument. While there is not a large body of research on the neuroscience of NPD, there are consistencies pointing to abnormalities in certain brain areas, especially the insular cortex, that are associated with features of NPD, especially lack of empathy. The origins of NPD remain unknown, however biological, psychological and social factors all play important roles in the etiology of this disorder. Further clinical and neuroscience studies of empathy disorders, especially NPD and malignant narcissism, are necessary in order to better understand the environmental factors that contribute to this disorder.