Websites, blogs, and message boards of the “manosphere” are dedicated to a worldview that celebrates hegemonic masculinity and decries feminism. In a reflexive thematic analysis of 227 posts (389,189 words) from two manosphere message boards (The Red Pill and Incel), we analyzed how posters viewed women and men. We found that beliefs about women and men formed an ideology comprised of (a) evolution‐based views of gender essentialism, (b) an informal psychology of women's motivations, and (c) a typology of men. Women were seen as having three primary motives: to deceive and manipulate men, to promiscuously satisfy their own sexual needs, and to trade sex for power. Men were seen as falling into two (The Red Pill) or three (Incel) types: alpha men who are attractive, powerful, and sexually successful, beta men who give to women as their only route to sexual interactions, and incel (involuntarily celibate) men who are too unattractive to achieve sexual success. Posters acted on these beliefs either to improve themselves (The Red Pill) or give up on life and endorse suicide and/or violence (Incel). We discuss these beliefs and actions in relation to theories of sexual aggression, the psychology of radicalization, and the American Psychological Association's Guidelines for Psychological Practice with Boys and Men.