Foundational:
- The Wealth of Nations
- The General Theory of Employment, Interest, and Money
- Capital
Modern:
- Capital in the Twenty-First Century
- Freakonomics
- Misbehaving: The Making of Behavioral Economics
- Thinking, Fast and Slow
- The Economics of Inequality
- Administrative Behavior
Accessible Intros:
- Naked Economics: Undressing the Dismal Science
- Economics in One Lesson
- The Undercover Economist
Diverse Perspectives:
- Poor Economics
- The Worldly Philosophers
- The Black Swan
- The Road to Serfdom
- Debt: The First 5000 Years
- The Constitution of Liberty
- Law, Legislation and Liberty
- The Fatal Conceit: The Errors of Socialism
- The Shock Doctrine: The Rise of Disaster Capitalism
A separate mention goes to "Non-Cooperative Games" which is not a book.
