Henry Stuart Hazlitt (; November 28, 1894 – July 9, 1993) was an American journalist, economist, and philosopher known for his advocacy of free markets and classical liberal principles. Over a career spanning more than seven decades, Hazlitt wrote extensively on business, economics, and public policy for prominent publications, including The Wall Street Journal, The Nation, The American Mercury, Newsweek, and The New York Times. He is best known for his 1946 book, Economics in One Lesson, a work grounded in the Austrian school of economics and its belief in the importance of individual liberty in economic decision-making.

Hazlitt was a strong proponent of hard currency and a vocal critic of inflationary practices and government intervention in markets. As a defender of free enterprise, he drew on the ideas of economists such as Ludwig von Mises and Friedrich Hayek, helping popularize their theories for a general audience. Beyond economics, Hazlitt contributed to debates on philosophy and ethics, advocating for what he argued were the moral underpinnings of a free society. He also served as an editorial board member of the libertarian journal The Freeman and was a founding member of the Foundation for Economic Education (FEE), one of the oldest free-market think tanks in the United States.

Throughout his life, Hazlitt's writing and commentary significantly influenced public understanding of economic policy, and his works continue to inspire advocates of liberty and limited government around the world. but grew up in relative poverty, his father having died when Hazlitt was an infant. His early heroes were Herbert Spencer and William James, and his first ambition was for an academic career in psychology and philosophy. He attended New York's City College, but left after only a short time to support his twice-widowed mother.

As he later wrote, his short time at college "had a greater influence than may at first sight be supposed, not as much from the knowledge gained there, as from the increased consciousness of the knowledge which I still had to gain and the consequent ambition to attain it." Hazlitt published his first book, Thinking as a Science at age 21. He wrote the book because he realized—through his intense process of self-education—that it was more important to think clearly than to merely absorb information. As he explains in its opening pages: