Since the 9/11 attacks by Al Qaeda members against the United States, counterterrorism has become a top priority for policymakers and academic researchers. A critical aspect of this mandate is the prevention and intervention of future terrorist attacks by U.S.-based jihadist and Salafist extremists. This study aims to generate a typology of homegrown terrorists who have been prosecuted by the United States federal government for terrorism offenses within the United States since the 9/11 attacks. The current study uses a sample of 115 cases, involving 194 offenders. Three clusters of offenders who share a set of demographic, social, and behavioral characteristics were identified through a two-step cluster analysis. These clusters include: Cyber Attackers, Convert Affiliates, and Trained Allies. Clusters also exhibited variation in the nature of terrorist activity and degree of operational success. The unique characteristics of each cluster suggest possible policy implications for international travel, cyber regulation, and community outreach programs to address the unique threats posed by subgroups of offenders. Efforts to prevent future terrorist plots and attacks may be more effective if the type of offender is considered.