11. Elon Musk
> Company: Tesla Motors Inc.
> Value of shares: $4.7 billion
> CEO since: 2008

PayPal founder Elon Musk is currently the CEO of both Tesla Motors Inc. (NASDAQ: TSLA), an electric car company, and SpaceX, a rockets and spacecraft company. Musk began running Tesla as CEO in 2008, just five years after he help found the company. Within two years, in 2010, Tesla went public and today is worth more than $20 billion. SpaceX was responsible for the first privately developed spacecraft — the SpaceX Falcon 1 — which successfully entered space and orbited around the Earth. Musk is a hands-on chief executive, who oversees and participates in design and development. He additionally served as chairman of alternative energy company SolarCity Corp.

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12. Michael Dell
> Company: Dell Inc.
> Value of shares: $3.8 billion
> CEO since: 2007

Michael Dell founded his namesake company in a college dorm room in 1984. By 1992, Dell was the youngest CEO at the time to make the Fortune 500 list. This year, Dell is poised to reacquire the PC maker for $24.9 billion. In the past several years, Dell Inc. (NASDAQ: DELL) has struggled, due in part to the rising popularity of smartphones and tablets, which has accelerated the decline of the PC market. As a private business, Dell will attempt to transition its focus towards providing software and enterprise services.

13. Ralph Lauren
> Company: Ralph Lauren Corp.
> Value of shares: $3.7 billion
> CEO since: 1967

Ralph Lauren founded what would become Ralph Lauren Corp. (NYSE: RL) in 1967, when the designer’s ties first appeared in department stores. From there, Lauren continued to develop new ideas, including using men’s fabrics for womens’ clothing and his famous polo shirt. In 1997, he took his company public. Presently, Ralph Lauren has multiple brands in addition to the well-known Polo Ralph Lauren, including luxury, athletic wear and denim-focused lines. The company also has two restaurants located in Chicago and Paris.

14. John Hess
> Company: Hess Corp.
> Value of shares: $2.3 billion
> CEO since: 1983

Leon Hess founded Hess Corp. (NYSE: HES) in 1933 as an oil delivery business near his home in New Jersey. With time, the company expanded beyond local delivery, purchasing oil tankers and building both oil terminals and refineries. By the 1960s, the company started opening gas stations and began offering its now-famous line of Hess truck toys. Leon Hess eventually was succeeded by his son, John. Recently, Elliott Management Corp., one of the company’s largest shareholders, heavily criticized John Hess and Hess Corp. for having a board of directors that was too entwined with the company’s management and the founding family. Elliott also accused Hess of poorly managing the company. In May, the dispute was settled with Hess being stripped of his role as chairman and the company overhauling its board of directors.

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15. Frederick Smith
> Company: FedEx Corp.
> Value of shares: $2.1 billion
> CEO since: 1977

Frederick Smith founded FedEx Corp. (NYSE: FDX) in 1971. He has served as either chairman, CEO or president, or some combination thereof, ever since. The company was a pioneer in combining air and ground express shipping. According to its website, in 1973, FedEx sent 14 Dassault Falcon jets to deliver packages across the nation on its first night of operations. Roughly 10 years later, FedEx became the first company in the country to surpass $1 billion in revenue without any merger and acquisition activity. Currently, FedEx has more than $44 billion in annual revenues and more than 300,000 employees. Smith’s ownership stake, totaling more than 6% of the company, is worth more than $2 billion.