John Maynard Keynes, 1st Baron Keynes, CB, FBA (1883 – 1946) British economist

His ideas have fundamentally affected the theory and practice of modern macroeconomics and informed the economic policies of governments. He built on and greatly refined earlier work on the causes of business cycles, and is widely considered to be one of the founders of modern macroeconomics and the most influential economist of the 20th century.[His ideas are the basis for the school of thought known as Keynesian economics, and its various offshoots.

Source: Wikipedia