William Penn Adair (1830–1880) was a leader of the Cherokee Nation, an attorney who served in political office both before and after the American Civil War, and as a justice of their court.
He entered the Confederate States Army on the promise that the Confederacy would support an Indian state if it won the war, and achieved the rank of colonel.
He served as delegate from the Nation to Washington, DC during the 1860s and 1870s.
Born in the traditional Cherokee territory in Georgia, he traveled as a child with his family on the Trail of Tears of Indian Removal from the Southeast to Indian Territory (now Oklahoma).