Focusing on three forms of biological threat - bioterrorism, biocrime and biohacking - the author examines the history of biowarfare and terrorism, including the ideologies and motives of violent extremist organizations. Groups drawn to biological aggression are discussed, along with the array of viruses, bacteria and toxins they might use in their attacks. The phenomenon of biocrime - biological aggression targeting individuals for personal rather than ideological reasons - is explored, along with the growing trend of biohacking, in which citizen scientists conduct bioengineering experiments in home-based and other nontraditional settings. Part II of the text presents case studies of bioterrorism and biocrime from the United States and Japan.