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6. Lockheed Martin

CEO: Marillyn A. Hewson
Company value: $44.5 billion

CEO of the world's largest defense company, Marillyn A. Hewson has been the CEO and president of Lockheed Martin since Jan. 1, 2013. Hewson has worked at Lockheed Martin for 30 years in several key corporate executive roles and leadership positions. She also serves on the boards of the Congressional Medal of Honor Foundation, the USO and the National Geographic Education Foundation.

Duncan Chard |Bloomberg | Getty Images, Inset: Andrew Harrer | Getty images