William Harrison Barnie (January 26, 1853 – July 15, 1900), nicknamed "Bald Billy", was an American manager and catcher in Major League Baseball. Born in New York City, he played as a right fielder in the National Association in 1874–75. In 1883 he became manager of the Baltimore Orioles of the American Association; he appeared as a backup catcher that season, and also played two games in 1886, but otherwise did not take the field. After leaving the Orioles following the 1891 season, he managed the Washington Senators (1892), Louisville Colonels (1893–94) and Brooklyn Bridegrooms (1897–98). His career managerial record consists of 632 wins and 810 losses. His best finish was third place with the 1887 Orioles.
Barnie died in Hartford, Connecticut at the age of 47, of pneumonia complicated by asthmatic bronchitis, and was buried at Green-Wood Cemetery in Brooklyn, New York.