This article is based on the idea that lone-wolf terrorists may have characteristics in common with two other types of lone-actor violent offenders: assassins and school attackers. We used data from U.S. Government-sponsored reports to compare the characteristics of these two groups. Despite obvious demographic differences, results indicate four characteristics common for both school attackers and assassins: perceived grievance, depression, a personal crisis (‘unfreezing’), and history of weapons use outside the military. These characteristics may be useful in distinguishing lone-wolfs from group-based terrorists.