éminence grise

• eminence grise, gray eminence, grey eminence

Borrowed from French éminence (“power”) + grise (“gray”)

éminence grise (plural éminences grises or éminence grises)

1. (idiomatic) A secret or unofficial decision-maker; the power behind the throne.
   • 1987 July 12, John A. Garraty, "Harry's Luck" (book review of Harry Hopkins: Ally of the Poor and Defender of Democracy by George McJimsey), New York Times (retrieved 4 Sep. 2011):

     But Harry Hopkins was no mere manipulator of people and ideas, no eminence grise masterminding the actions of figureheads.

   • 2009 Sept. 16, Coco Masters, "New Prime Minister — and New Shadow Shogun," Time:

     Ozawa is the Secretary-General of Hatoyama's Democratic Party of Japan (DJP) and the éminence grise of the electoral campaign that catapulted the new Prime Minister to power.

• IPA^(key): /e.mi.nɑ̃s ɡʁiz/

éminence grise f (plural éminences grises)

1. (idiomatic) éminence grise