If you are not familiar with the works of Hans-Hermann Hoppe–well, you should be, as he is the leading social theorist, economist, and libertarian philosopher of our time (IMHO). Check out these classics: his tour de force Book Review of Man, Economy, and Liberty: Essays in Honor of Murray N. Rothbard, published back in 1989, when he was just bursting onto the Austrian-libertarian scene; his Introduction to his latest blockbuster work, Democracy: The God That Failed; his summary of Rothbardian Ethics; a ringing defense of the justice and feasibility of anarchy, The Private Production of Defense; and brilliant sociological-historical-economic analysis, Banking, Nation States and International Politics: A Sociological Reconstruction of the Present Economic Order.
Also not to be missed are Hoppe’s radical, realist, neo-Kantian/Misesian epistemological views, e.g. in Economic Science and the Austrian Method; In Defense of Extreme Rationalism; and On Certainty and Uncertainty, Or: How Rational Can Our Expectations Be?. And last, but certainly not least, his groundbreaking apriori, praxeological defense of libertarian rights, in his “argumentation ethics“.