Business corporations are important, often powerful actors within the economy. They are able to exercise power over other actors, such as employees, consumers and nation-states. This contribution discusses how corporate power is constituted (ontological question), for what purpose it should be exercised, (normative question) and how it should be controlled (governance question). It focuses on the competing anwers to these questions that have been proposed by three political theories of the corporation. Concession theories emphasize the state's role in chartering corporations, (...) and hence require corporations to act in the public interest. Contractualist theories present corporations as tools for contract partners (most often shareholders), with corporate purpose focused on the benefits to these partners. Real entity theories focus on the corporation as an autonomous, separate entity with a purpose to be determined by the group seeking incorporation. (shrink)