Objective: Although violent extremism is often attributed to clinical (dysfunctional) dispositions, it is also possible that violent Jihadists might be clinically “normal” but bear certain personality signatures. This alternative view has yet to be tested. Method: In six studies, employing hard-to-reach Muslim samples, including one study of former Mujahideen, we investigated the relationship between basic personality traits and violent extremism. We further used a known group paradigm to validate the personality signatures of violent extremism, comparing a sample of former Mujahideen with another sample from Afghanistan. Results: These studies and an internal meta-analysis revealed that Lower Openness to Experience, lower Emotionality, and lower Altruism were associated with more violent intentions to support Muslims. Higher Altruism was associated with higher levels of nonviolent intention to support Muslims. Supporting the validity of the nonviolent intention measure, similar associations were found in Study 3 with overt behavioral support of Muslims (donations). More important, compared to the nonMujahideen, the Mujahideen sample scored lower on average on, for instance, Openness, indicating that these results go beyond self-reported, findings. Conclusion: We demonstrated that personality predicts violent and nonviolent defense of Muslims among four general populations of Muslims living in the West and in Asia (including the Middle East), and a sample of Mujahideen in Afghanistan.