Thomas Nagel (/ˈneɪɡəl/; born July 4, 1937) is an American philosopher, currently University Professor of Philosophy and Law Emeritus at New York University in the NYU Department of Philosophy, where he has taught since 1980. His main areas of philosophical interest are philosophy of mind, political philosophy and ethics.

Nagel is well known for his critique of reductionist accounts of the mind, particularly in his essay "What Is it Like to Be a Bat?" (1974), and for his contributions to deontological and liberal moral and political theory in The Possibility of Altruism (1970) and subsequent writings. Continuing his critique of reductionism, he is the author of Mind and Cosmos (2012), in which he argues against a reductionist view, and specifically the neo-Darwinian view, of the emergence of consciousness.

Derived from Thomas Nagel's Locke Lectures, Equality and Partiality proposes a nonutopian account of political legitimacy, based on the need to accommodate both personal and impersonal motives in any credible moral theory, and therefore in any political theory with a moral foundation. Within each individual, Nagel believes, there is a division between two standpoints, the personal and the impersonal. Without the impersonal standpoint, there would be no morality, only the clash, compromise, and occasional convergence of individual perspectives. It is because a human being does not occupy only his own point of view that each of us is susceptible to the claims of others through private and public morality. Political systems, to be legitimate, must achieve an integration of these two standpoints within the individual. These ideas are applied to specific problems such as social and economic inequality, toleration, international justice, and the public support of culture. Nagel points to the problem of balancing equality and partiality as the most important issue with which political theorists are now faced.