Sir Ewen Cameron KCMG FRGS (23 June 1841 – 10 December 1908) was a Scottish merchant banker and chartered accountant of the late 19th century, who rose to be chairman of Hong Kong and Shanghai Bank in London.He played a key role in arranging loans from the Rothschild family to the Empire of Japan during the Russo-Japanese War. He is the patrilineal great great grandfather of David Cameron.