26. Rob and Jim Walton

Titles: Board members and controlling shareholders, Walmart

Country: US

Ages: 71 (Rob) and 67 (Jim)

Rob and Jim Walton control perhaps the most powerful company on earth in the mega-retailer Walmart, which employs 2.2 million people in 28 countries and generates annual revenues of $486 billion. Combined, the Walton brothers' fortunes are worth more than $60 billion.

Their father, founder Sam Walton, warned his children not to sell their stakes and to keep the company under family control, writing in his book, "If you start any of that foolishness, I'll come back and haunt you." Sam and Rob have heeded his wishes. While neither manages day-to-day operations, both sit on the board, and the company remains majority-owned by the Walton family.

Rob stepped down as chairman of the company in June 2015 after 23 years on the job, and his son-in-law Gregory Penner succeeded him. The company, long maligned for its low pay, announced in February 2015 it would increase wages for 500,000 US employees.