The works of Galen of Pergamum (c. 129-216 CE) were fundamental in the shaping of medicine, philosophy, and neighboring areas of knowledge from antiquity through to the middle ages and early modern times, across a variety of languages and cultures. Yet as early as Galen's own lifetime, spurious treatises crept into the body of his authentic works, despite his best efforts to provide the public with a catalogue of his own production (De libris propriis). For centuries, readers and scholars have used a fluid body of Galenic works, shaped by changing intellectual frameworks and social-cultural contexts. Several inauthentic works have enjoyed remarkable popularity, but this has had consequences in modern scholarship. The current reference edition of Galenic works (Kühn, 1821-1833) fails to distinguish clearly between authentic and inauthentic texts, and many works lack any critical study, which makes navigating the corpus unusually difficult. This new volume, arising from a conference held in 2015 at the Warburg Institute at the University of London and funded by the Wellcome Trust, will provide much-needed clarification about the boundaries of the Galenic corpus, identifying and analyzing the works that do not genuinely belong to Galen's production.