Net worth: $58.5 billion

Age: 32

Country: US

Industry: Technology

Source of wealth: Self-made; Facebook

In 2004, Mark Zuckerberg, then a 19-year-old sophomore at Harvard, launched TheFacebook.com, a rudimentary version of the now ubiquitous social network known as Facebook. Zuckerberg dropped out of college to work full-time as Facebook's CEO, and the site quickly exploded in popularity. Today, it attracts more than a billion users daily and is worth nearly $400 billion. At 32, Zuckerberg is by far the youngest of the 50 richest people in the world. His wealth has increased by $11.1 billion in the past year. 

In December 2015, Zuckerberg and his wife, Priscilla Chan pledged give away 99% of their wealth in their lifetimes through an organization called the Chan Zuckerberg Initiative, though some critics noted the organization wasn't a nonprofit charity itself and found the announcement misleading.

But this isn't the couple's first foray into philanthropy. They donated $25 million in the fight against Ebola in 2015, and they gave $100 million worth of Facebook shares toward improving a New Jersey public-school system.