powerbroker

or pow·er bro·ker

[ pou-er-broh-ker ]
/ ˈpaʊ ərˌbroʊ kər /

noun

a person who wields great political, governmental, or financial power.

Origin of powerbroker

An Americanism dating back to 1960–65; power + broker
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for power broker

power broker

noun

a person with power and influence, esp one who operates behind the scenes

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012