eminence grise

‘Grey eminence’. A person who exercises power or influence in certain areas despite any appropriate rank. Named after Cardinal Richelieu’s right hand man, François Leclerc du Tremblay, who wore beige attire (known as grey). Historical examples who have received such description are 16th century Catherine de Medici of France, Imperial Chinese Empress Dowager Cixi, Hitler’s private secretary Martin Bormann, post WWII Italian party leader Giulio Andreotti, and US vice president Dick Cheney.