Betty Sue Hearnes (née Cooper; born July 24, 1927) is a Democratic American politician from Missouri. She married Warren E. Hearnes, a recent West Point graduate, on July 2, 1948, while he was on leave from the United States Army, and was his partner throughout his career, including his two terms as Governor of Missouri and the federal investigations of his conduct by the Nixon White House, until his death in August 2009. She was elected to the Missouri House of Representatives from Charleston in 1979, in a special election. She was re-elected in 1980, 1982, 1984, and 1986.