This Research Note presents the outcome of a project that looked at the personal characteristics of lone-actor terrorists. It is part of the larger Countering Lone-Actor Terrorism (CLAT) project. The project described here aimed to improve understanding of, and responses to, the phenomenon of (potentially) violent lone-actors based on an analysis of 120 cases from across Europe. The Research Note focuses on the personal characteristics of lone-actor terrorists. First of all, it presents the main findings of the general analysis of the study into personal variables of lone-actor terrorists. Subsequently, the authors outline a set of recommendations based on the key findings. In the beginning, we present the main research questions of the CLAT project and the working definition of lone-actor terrorism.