The hallmark of the delusional misidentification syndromes is the presence of a misidentification delusion of the self or others. Delusional misidentification may present with an increased risk for dangerous behaviors. Individuals suffering from delusional misidentification syndromes may express hostility in ways ranging from serious verbal threats to homicidal acts. The causes of dangerous misidentification delusions remain for the most part undetermined. In this article, we report a series of six cases of individuals who harbored dangerous misidentification delusions. These individuals were studied phenomenologically and forensically. They were also studied biologically, including neuropsychological testing. A cognitive hypothesis aimed at explaining dangerousness and delusional misidentification is proposed. Implications of the hypothesis for further research are briefly outlined.