Robert Michael Duncan (born 1951) is a Kentucky Republican who served as the chairman of the Republican National Committee from 2007 to 2009. Throughout his career, he has served on the boards of a variety of public- and private-sector organizations. Duncan was chairman, president, and CEO of Inez Deposit Bank in Inez, Kentucky, which merged with First State Bank in February 2021. He is a member of the Board of Governors of the U.S. Postal Service and previously served as its chairman.