Hannah Arendt was a key intellectual figure of the twentieth century, whose writings have impacted philosophy, political theory, and the social sciences. Although she held sociology in low regard, her ideas have had significant influence within the field. Her engagements with totalitarianism, social movements, power, politics, morality, evil, and the self have shaped how sociologists have taken up these subjects, and her style of theorizing presents important challenges to sociological theory. This entry discusses her contributions in each of these areas, with particular emphasis on their significance for sociology.