This two-volume companion brings together a team of contemporary theologians and writers to provide substantial introductions to the key people who shaped the Christian story and tradition. This is a substantial new two-volume reference work, bringing together over 75 entries on the most important and influential theologians in the history of Christianity. It is structured accessibly around five periods: early centuries, middle ages, reformation period, the Enlightenment, and the twentieth-century to the present. A to Z entries range from substantial essays to shorter overviews, each of which locates the theologian in their immediate context, summarizes the themes of their work, and explains their significance. This book covers a broad span of theologians, from Augustine to Thomas Aquinas, through to C. S. Lewis, James Cone, and Rosemary Radford Reuther. It provides profiles of key Catholic, protestant, evangelical, and progressive theologians, and includes a useful timeline to orientate the reader, reading lists, and a glossary of key terms.