Marginal figures, from heretics, ascetics and mystics to saints, visionaries and witches have played key roles in decisive mutations of religious authority in the history of different forms of Christianity. This book offers new theoretical perspectives on the theme of marginality in a series of in-depth case studies of marginal figures and forms of marginality. It presents a distinction between social marginality, often resulting from social exclusion and demonization as well as involving discomfort and distress, and religious marginality, which can be voluntary, actively sought out, and performed. The contributions analyse both social and religious forms of marginality and demonstrate how a focus on media is crucial for understanding the role of marginality in authority mutations in the long history of Christianity. The articles discuss a wide range of media, from amulets, space, technologies of the self, literary forms, to visual culture and mass and social media. The book thus offers media-based pointers for comparative, historical studies more broadly in the study of religions.