August Belmont, Prussian-American financier and diplomat, 16th United States Ambassador to the Netherlands (d. 1890)

August Belmont Sr. (born August Schönberg; December 8, 1813 – November 24, 1890) was a German-American financier, diplomat, politician and party chairman of the Democratic National Committee, and also a horse-breeder and racehorse owner. He was the founder and namesake of the Belmont Stakes, third leg of the Triple Crown series of American Thoroughbred horse racing.