mover and shaker

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One who wields power and influence in a sphere of activity.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun idiomatic someone who has power and influence in some field or activity.
• noun idiomatic The people in an organization who are most responsible for getting things done.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a person who wields power and influence