This book explores the relationship between the personality of political leaders, its interaction with top leadership positions and its impact on the respective parties' electoral performance and organization. It focuses on the less-investigated region of Eastern Europe and includes chapters on Bosnia-Herzegovina, Bulgaria, Croatia, Czech Republic, Georgia, Hungary, Poland, Montenegro, Romania, Serbia and Slovakia. Each chapter compares and contrasts two party leaders with at least two terms in office between 1991 and 2019. The book applies systematically a common theoretical and methodological framework across leaders and countries, thus providing rich empirical evidence.