"William Duncan" may refer to:

*William fitz Duncan (died 1147), Scottish prince and general

*William Duncan (missionary) (1832–1918), English-born Anglican missionary

*William Addison Duncan (1836–1884), U.S. Representative from Pennsylvania

*William Garnett Duncan (1800–1875), U.S. Representative from Kentucky

*William Henry Duncan (1805–1863), English doctor and Britain's first Chief Medical Officer

*William Wallace Duncan (1839–1908), American bishop of the Methodist Episcopal Church, South, elected in 1886

*William Duncan (actor) (1879–1961), actor and director of film serials

*William Dow Duncan (1892–1961), New Zealand rugby player

*Art Duncan (William James Arthur Duncan, 1894–1975), World War I flying ace

*William Duncan (footballer) (born 1913), Scottish association football player

*William Duncan (philosopher) (1717–1760), Scottish natural philosopher and classicist

*William Butler Duncan (1853–1912), New York City banker

*William Augustine Duncan (1811–1885), Scottish journalist and colonial official

*William C. Duncan (1820–1877), brewer, politician, and mayor of Detroit, Michigan

More William Duncan on Wikipedia.