William Zahn married Winyan Waste, a sister of John Grass. They had two sons, John Zahn and William Zahn.
William Zahn married (Princess) Kezewin (Josephine) Cloud, daughter of Chief Flying Cloud and a relative of Sitting Bull.They had three sons and six daughters. He was an Interpreter and was a soldier at Standing Rock Agency. He was in fact one of the 26 soldier who first help in the establishment of Fort Yates in 1873.In 1874 he was with Custer;s Company G, 17th U.S. Infantry on the expedition to the Black Hills to see if there was gold there. In 1898 he was with Buffalo's Bill's Wild West Show in Chicago as interpreter at the display of Sitting Bull' cabin. He was also Indian trader.