William Frederick Nast (1840–1893) was an American diplomat and entrepreneur.
He was the third president of the Atchison, Topeka and Santa Fe Railway.Nast was born in Cincinnati, Ohio, on June 14, 1840, the son of Methodist religious leader William Nast.
From 1861 to 1865 he served at the American Consulate in Stuttgart, Germany.
Upon his return to the United States, Nast entered the brokerage business in New York, New York.
On September 2, 1868, Nast became president of the Atchison, Topeka and Santa Fe Railway, a position he held for less than a month, ending on September 24, 1868.
Also in 1868, he married Esther A.