Walter W. Stewart
From the History of Political Economy:
[Walter] Stewart served as a top adviser to policymakers before there was any tradition for such service by economists. Despite minimal formal academic training in economics, he had the good fortune to become closely associated with Davenport, Walton Hamilton, and Veblen in his early years, to work under Wesley Mitchell at the end of World War I, and to acquire a strong taste for empirical work, to produce an imposing group of students at Amherst, and to gain the friendship and confidence of dignitaries like Benjamin Strong and Dwight Morrow. Concluding his career with service on the Council of Economic Advisers was really a tribute to his pioneering work in the 1920s.