Bill Gates (net worth: $86.9 billion)

The world’s richest person from 1995 to 2007, again in 2009, and again since 2014, Bill Gates co-founded Microsoft, the world’s biggest software maker, and owns a 2.5 percent stake in the Redmond, Washington-based company. The rest of his fortune is managed through closely held Cascade Investment, which controls stakes in dozens of publicly traded companies, including Canadian National Railway, Deere, and Ecolab.