Alasdair MacIntyre (born 1929 in Glasgow) is a Scottish philosopher known mostly for his contributions to moral philosophy. He was educated at the institution now known as Queen Mary, University of London and the University of Manchester, and is currently a Senior Research Professor of Philosophy at The University of Notre Dame, Indiana, USA. MacIntyre has been something of an intellectual nomad, having taught at many universities in the US, including Boston University, Duke University, Brandeis University, and Vanderbilt University. He is a former president of the American Philosophical Association and is married to the philosopher Lynn Joy. In April 2005 he was elected to the American Philosophical Society.

Academic philosophers, students and non-academic observers, who have made MacIntyre one of the most widely read contemporary philosophers, absorb his work primarily because he excels at presenting complicated and historically controversial philosophical challenges in simple to understand narratives where adversaries are compared by their philosophical assumptions, questions and intellectual histories. Whereas many contemporary philosophers advance philosophical positions by focusing on the logical, analytical or so called scientific underpinnings, MacIntyre often appeals to the plain light of ordinary story telling (through insightful historical reconstruction) to resolve complicated issues in the areas of moral philosophy, intellectual history, ethics, practical reason, Aristotle, Collingwood and Thomas Aquinas. It's fair to say MacIntyre is one of many thinkers whose work benefited greatly from the influence of the study of historical thinking on the practice of philosophy in the Western Tradition. Croce, Hegel, Heidegger, Collingwood and others should be credited for contributing to this phenomenon.

More specifically, MacIntyre is a key figure in the recent surge of interest in virtue ethics, which identifies the central question of morality as having to do with how one should live one's life. This is an approach to philosophy that can accurately be compared to other moral systems by scope. MacIntyre and his supporters (both influencers and advocates) focus on moral problems as those having to do with how to make the most of an entire human life whereas most non-MacIntyre-ites focus on more granular, sharply focused ethical debates such as abortion, homosexual political rights, etc. MacIntyre is not silent on such matters, however, he does approach them from a wider context and less rule based standard.