10. Bill Gates

Title: Cochair and trustee, Bill and Melinda Gates Foundation

Country: US

Age: 60

Gates cofounded Microsoft in 1975 with childhood friend Paul Allen, building an iconic software company and becoming the richest man on earth in the process, with a net worth of $87.3 billion. Though he still sits on the company’s board, he’s no longer actively involved in Microsoft.

Instead, Gates is fixated on giving away his wealth and running one of the most powerful charities in the world with his wife, Melinda. They founded the Bill and Melinda Gates Foundation in 2000 after reading an article about curable diseases causing millions of child deaths in developing countries.

Since then, the organization has given away $34.5 billion to an array of causes, including efforts to eliminate HIV, malaria and many other infectious diseases. They also support agricultural development, emergency relief, global libraries, urban poverty, and education.

Gates and good friend Warren Buffett started the Giving Pledge to encourage billionaires to follow their lead and give away half or more of their wealth — 135 have signed up.