William Emlen Roosevelt (April 30, 1857 – March 15, 1930) was a prominent New York City banker who held a wide range of positions in numerous organizations and was a cousin of United States President Theodore Roosevelt. He was president of Roosevelt & Son, the banking firm founded by his father James Alfred Roosevelt.[1] He was director of the Chemical Bank of New York, the Gallatin National Bank, and the Astor National Bank,[1] and later sat on the boards of the Grand Hanover and the Bank of New York.[2] He was president of Roosevelt Hospital, founded by his distant cousin James H. Roosevelt.[1] He was an officer of the National Guard for 16 years, major and quartermaster of the First Brigade.[2] Roosevelt became involved in telecommunications companies, formed the Mexican Telegraph Company and Central and South American Telegraph Company, and was eventually director of the International Telephone and Telegraph Company.[2] He also owned the James Alfred Roosevelt Estate at Cove Neck in Nassau County, New York.[3]
Theodore Roosevelt and he had a very close relationship as cousins. Emlen was not interested in politics other than to support his cousin's bids for public office, and Theodore, busy with conservation advocacy, had little time to attend to financial matters. Thus, "Cousin Emlen" was Theodore's financial adviser before, during and after his presidency.[2]