This introductory chapter provides a rationale for the book, reviews some of the key theoretical underpinnings of posthumanism and new materialism and outlines how they have influenced feminist theorising in relation to debates about the subject, sex, gender, sexual difference, the body, affect, relationality, matter, agency, human and other-than-human entanglements, ecology and technology. The implications of these feminist engagements with posthumanism and new materialism for critical studies of men and masculinities are considered and a posthuman feminist critique of the subject of ‘Man’ as the ideal human is outlined. The authors reflect upon their own biographical intellectual and political journeys of engagement with these issues to ground these debates in their own shifting subjectivities. The chapter concludes with a guide to chapters by the contributors who, from a diverse range of disciplinary backgrounds, bring these theoretical perspectives to life in their own considerations of what posthumanism and new materialism mean for the ‘man question’.