註釋 This thesis represents the first monograph on Cassius the tyrannicide for almost a century, and the only one in English. It provides a detailed treatment of his career down to 44 BC, and, in particular, re-assesses Cassius' role in Caesar's assassination. It is organised into six chapters. Chapter One examines the problematic source tradition, which displays notable biases regarding Cassius. Chapter Two explores Cassius' ancestry and family. And Chapters Three through Six assess Cassius' life and career down to the assassination, focusing in particular on the following episodes: his service under Crassus and after Carrhae; his actions during the civil war between Caesar and Pompey; and his role in the conspiracy against Caesar. A series of Appendixes provide supplementary information on Cassius and his family. The thesis concludes that Cassius was the architect of the conspiracy against Caesar, and should be considered a Republican figure whose historical significance is equal to --if not more important than-- Brutus'. 