Net worth: $47.9 billion

Age: 81

Country: US

Industry: Diversified investments

Source of wealth: Inheritance/self-made; Koch Industries

Charles Koch is chairman and CEO of multifaceted conglomerate Koch Industries, the second-largest private company in America. His younger brother David is the executive vice president. The company employs 100,000 people and generates $100 billion in sales from its diverse holdings, which make everything from petrochemicals and Dixie Cups to raw clothing materials. 

Outspoken in the world of conservative politics, the Koch brothers, who have a combined net worth of $95.8 billion, routinely fund political campaigns, although they took a step back during the 2016 election cycle. 

However, in "Dark Money: The Hidden History of the Billionaires Behind the Rise of the Radical Right," it was revealed that Charles Koch's plans to reshape American politics date back 40 years, when he began strategizing and developing a libertarian movement.