This chapter provides an introduction of the most influential theories of normative ethics: virtue ethics, duty ethics, and utilitarian ethics. It does so by following three prominent philosophers, Aristotle, Kant, and Bentham, while also stressing that the ideas discussed are not limited to their works or confined to Western philosophy. The approaches depart from different perspectives, namely from the good person, the righteous person, and the useful person. They have also been developed in particular sociotechnical contexts, in which medical skill, mechanical clockworks, and factories and prisons co-shaped our ethical thinking. The chapter concludes by showing how the ethical theories may be applied to evaluate the impacts of emerging technologies.