The incel community displays characteristics of an extremist group that spreads radical beliefs promoting violence against women and society. Their online forums are breeding grounds for radicalization by spreading misogyny, hatred, and a sense of victimization that justifies hostility toward outsider groups. While not all incels espouse or act violently, the rise of violent attacks by self-proclaimed incels, aimed at disrupting gender roles and social order, has led experts to debate whether their actions constitute terrorism. The incel community believes individuals’ worth and success in life are determined primarily by uncontrollable factors like genetics, not personal choice or responsibility. They insist they are marginalized and doomed to isolation due to society’s and women’s unfair standards. This “external locus of control” and belief in their own aggrieved entitlement to sex and relationships justify their hostile views. The spread of these grievances as popular tropes within the incel community’s “radical milieu” enables radicalization. Monitoring how these ideas evolve and weaponize within the radical milieu is key to understanding and countering the threat. Responses should aim to change social norms by promoting inclusiveness, empowering women’s voices, and educating officials and the public. They should also identify and support at-risk individuals, while monitoring threats and policing illegal behavior. Some argue against labeling incel violence as terrorism or “securitizing” the issue, but doing so elevates it, ensures proper resourcing, and provides existing policy tools to tackle the problem. Approaches should avoid broad categorization or creating “suspect communities,” instead focusing on specific behaviors and beliefs that promote violence. Understanding the root causes of incel radicalization and addressing broader societal misogyny are also paramount to preventing future attacks. The rise of the incel movement and associated violence highlight the need to prioritize research on gender and sexuality in studies of radicalization and extremism. Monitoring evolving incel beliefs and the spread of tropes justifying violence within their radical milieu can aid prevention. Overall, the incel phenomenon requires comprehensive study to determine appropriate responses balancing security, inclusiveness, and civil liberties.