The Nicomachean Ethics is the name normally given to Aristotle's best-known work on ethics. It is widely considered one of the most important historical philosophical works, and had an important impact upon the European Middle Ages, becoming one of the core works of medieval philosophy. It therefore indirectly became critical in the development of all modern philosophy as well as European law and theology.

The theme of Nicomachean Ethics is a Socratic question previously explored in the works of Plato, Aristotle's friend and teacher, of how men should best live. Ethics, as now separated out for discussion by Aristotle, is practical rather than theoretical, in the original Aristotelian senses of these terms. Ethics is about how individuals should best live, while the study of politics is from the perspective of a law-giver, looking at the good of a whole community.