Ronald Harry Coase (/ˈkoʊs/; born 29 December 1910) is a British-born, America-based economist and the Clifton R. Musser Professor Emeritus of Economics at the University of Chicago Law School. After studying with the University of London External Programme in 1927–29, Coase entered the London School of Economics, where he took courses with Arnold Plant. He received the Nobel Memorial Prize in Economics in 1991.

Coase is best known for two articles in particular: "The Nature of the Firm" (1937), which introduces the concept of transaction costs to explain the nature and limits of firms, and "The Problem of Social Cost" (1960), which suggests that well-defined property rights could overcome the problems of externalities (see Coase Theorem). Coase is also often referred to as the "father" of reform in the policy for allocation of the electromagnetic spectrum, based on his article "The Federal Communications Commission" (1959), where he criticizes spectrum licensing, suggesting property rights as a more efficient method of allocating spectrum to users. Additionally, Coase's transaction costs approach is currently influential in modern organizational economics, where it was reintroduced by Oliver E. Williamson.