Mark Zuckerberg (net worth: $50.3 billion)

Born in 1984, Mark Zuckerberg is the youngest billionaire on the list. A generous philanthropist, Zuckerberg is co-founder and chief executive officer of Facebook, the world’s largest social-networking company. The site has more than 1.5 billion monthly users and had revenue of $18 billion in 2015. The Menlo Park, California-based company’s initial public offering in 2012 was the biggest-ever technology IPO at the time.