Can democracy survive in a context of increasing inequality, macroeconomic disruption, political polarization, corporate media, fragile job security, and fiscally unstable welfare systems? This dissertation argues that the challenges facing Western democracies extend from a broader challenge, which I refer to as the “oligarchic challenge” to democracy. How do super-rich oligarchs use their material resources to gain political influence? How do oligarchs threaten to erode democratic norms and institutions, even as they operate alongside of them? How can democratic publics vigorously contain oligarchs without succumbing to destructive forms of nationalism and populism? How should the history of democratic struggles against oligarchy inform contemporary praxis? This dissertation addresses these questions using normative, conceptual, historical, and institutional methods. First, the dissertation seeks to understand how best to conceptualize oligarchic power, recognizing that oligarchy and democracy have a complex and intertwined relationship. Second, it seeks to understand how oligarchic power has persisted in different historical contexts, and how the specter of oligarchy has inflected the work of canonical political philosophers operating from different ideological orientations: from ancient Greek virtue ethicists like Aristotle, to nineteenth-century utilitarian reformers like Jeremy Bentham and John Stuart Mill, to twentieth-century American social scientists like C. Wright Mills. Finally, it seeks to reflect upon some of the institutional processes which might enable ordinary “plebeian” citizens to contain oligarchic power.