John William Middendorf II (born September 22, 1924) is a former Republican United States diplomat. John William Middendorf II received a Bachelor of Naval Science degree from College of the Holy Cross in 1945. In World War II he served in the Navy (1944-1946) as engineer officer and navigator aboard USS LCS(L) 53, being mustered out in 1946. He became an investment banker and in 1963 in partnership with Austen Colgate formed his own company, Middendorf, Colgate and Company (with a seat on the New York Stock Exchange).