At the time of his death in January 2017, Derek Parfit was widely regarded among philosophers as the best and most important moral philosopher in well over a century. He was also both legendarily eccentric and legendarily generous. In his later years he became increasingly reclusive in his obsessive struggle to develop his ideas and arguments about an extensive set of philosophical problems before he died. His perfectionism, meticulous concern for the truth, and openness to being proved wrong prevented him from being satisfied until he had a convincing response to every possible objection to the views he sought to defend. Because Parfit was so reclusive, there were relatively few people who knew him well. In this volume of essays devoted to exploring his legacy, many of those to whom he was closest offer portraits of both the man and the philosopher. The overall result is a tapestry of largely converging but also in places slightly conflicting perceptions. The authors include his widow (also a philosopher), his sister, and a substantial proportion of his closest friends, all of whom were both his colleagues in philosophy and some of whom were also his former students. The volume is thus part intellectual biography and part memoir.