Addison Clay Harris (October 1, 1840 – September 2, 1916) was a lawyer and civic leader in Indianapolis, Indiana, who served as a Republican member of the Indiana Senate (1876 to 1880) and a U.S.
Envoy Extraordinary and Minister Plenipotentiary (ambassador) to Austria-Hungary (1899 to 1901).
The Wayne County, Indiana, native graduated from Northwestern Christian University (present-day Butler University) in 1862 and was admitted to the bar in 1865, the same year he established a law partnership with John T.
Dye in Indianapolis.
Harris was a founding member (1878) and president (1883 and 1890) of the Indianapolis Bar Association; a founder and president (1899 to 1904) of the Indiana Law School, which was a forerunner to the Indiana University Robert H.
McKinney School of Law in Indianapolis; a presidential elector in 1896; president of the Indiana State Bar Association (1904); a member (1905–1916) and president (1909 to 1916) of Purdue University's board of trustees; and a member of the Indiana Historical Society and the Columbia Club.