Objective: This research examines the interface between ideological passion and the dark tetrad personality traits to predict violent (vs. peaceful) political activism. Meta-analytic research shows that ideological obsessive passion (OP) is one of the strongest psychological factors associated with violent activism. Here, we examine whether this relationship is magnified by the dark tetrad (i.e., Machiavellianism, narcissism, psychopathy, and sadism), which have often been associated with antisocial behavior. Method: In Studies 1A-C, the interaction between ideological passion and the dark tetrad was tested cross-sectionally with three distinct ideological groups, namely, Democrats (N = 566), Republicans (N = 479), and Black Lives Matter supporters (N = 204). In Study 2, we tested the same model using an experimental manipulation of obsessive (vs. harmonious) passion in a sample of environmentalists (N = 233). Results: In Studies 1A-C, the relationship between OP and violent activism was systematically accentuated by sadism. Of note, these effects were specific to violent activism and unrelated to peaceful activism. In Study 2, we replicated these findings and showed that the relationship between sadism and violent activism was significant when individuals were in an obsessively (but not harmoniously) passionate mindset. Conclusion: These results shed light on the interplay between motivation and personality traits to predict violent activism.