William Henry Harrison Miller (September 6, 1840–May 25, 1917) was an American lawyer and Attorney General of the United States.

Born in Augusta, New York, Miller graduated from Hamilton College in 1861. He studied law in the office of Chief Justice Morrison Waite, and was admitted to the bar in Peru, Indiana in 1865. Miller practiced in that city for a short time, and was also the county school examiner. For many years, he was an advisor to General Benjamin Harrison. In 1889, President Harrison made Miller Attorney General. He was Attorney General until 1893.

Miller died in 1917 in Indianapolis, Indiana, and is buried in Crown Hill Cemetery in that city.