Four women have been conventionally framed as wives and/or mistresses and/or sexual partners in the biographical reception of Karl Marx (1818–1883) and Friedrich Engels (1820–1895) as heterosexual men. These women were Jenny Marx (née von Westphalen) (1814–1881), Helene Demuth (“Lenchen”) (1820–1890), Mary Burns (1821–1863), and Lydia Burns (1827–1878). How exactly they appear in the few contemporary texts and rare images that survive is less interesting than the determination of subsequent biographers of the two “great men” to make these women fit a familiar genre, namely intellectual biography. An analysis of Marx–Engels biographies shows how this masculinized genre enforces an incuriosity that makes gendered political partnerships unthinkable and therefore invisible. By contrast, a positive interest in these women, which rethinks what a gendered political partnership is or could be, results in a significantly different view of the two men. As historical figures, they shift from being individualized or paired‐with‐each‐other “great thinkers” to communist/socialist activists working in and through everyday spaces and material practices. Their pamphlets, articles, and books thus appear more as immediate political interventions and less as timeless theorizing or as the raw material for such intellectualizing reconstructions.