#20 Sergey Brin
Net worth: $29.2 billion
Lost $2.6 billion since 2014; dropped 1 spot on the Forbes list
Brin in the co-founder of Google, along with Larry Page.
#19 Larry Page
Net worth: $29.7 billion
Lost $2.6 billion since 2013; dropped 2 spots on the Forbes list
Page is the co-founder of Google, along with Sergey Brin.
#18 Sheldon Adelson
Net worth: $31.4 billion
Lost $6.6 billion since 2013; dropped 10 spots on the Forbes list
Shares of casino tycoon Sheldon Adelson's Las Vegas Sands Corp. were down 30% this year, largely due to a crackdown in Macau, where the company runs several properties.
#17 Li Ka-Shing
Net worth: $33.3 billion
Gained $2.3 billion since 2014; jumped 3 spots on the Forbes list
The richest man in Asia, Ka-Shing currently serves as chairman of Hutchison Whampoa, a conglomerate with interests in shipping and construction. He also holds a major real estate portfolio.
#16 Mark Zuckerberg
Net worth: $33.4 billion
Gained $4.9 billion since 2014; jumped 5 spots on the Forbes list
Zuckerberg is the founder and CEO of Facebook.
#15 Jeff Bezos
Net worth: $34.8 billion
Gained $2.8 billion since 2014; jumped 3 spots on the Forbes list
Bezos is the founder and CEO of e-commerce giant Amazon.
Disclosure: Bezos is an investor in Business Insider.
#14 Michael Bloomberg
Net worth: $35.5 billion
Gained $2.5 billion since 2014; jumped 2 spots on the Forbes list
Bloomberg, the former mayor of New York City, is the founder, CEO, and majority owner of Bloomberg LP.
#13 Bernard Arnault and family
Net worth: $37.2 billion
Gained $3.7 billion since 2014; jumped 2 spots on the Forbes list
Arnault and his family hold a 46% stake in LVMH Moet Hennessy Louis Vuitton, the world's largest maker of luxury goods.
#12 Samuel Robson Walton
Net worth: $39.1 billion
Gained $4.9 billion since 2014; jumped 2 spots on the Forbes list
A member of the founding family of Walmart, Walton has served as the head of the retail giant's board since 1992.
#11 Alice Walton
Net worth: $39.4 billion
Gained $5.1 billion since 2014; jumped 2 spots on the Forbes list
Walton, a daughter of Wal-Mart founder Sam Walton, is an heiress to the big box store fortune.
#10 Liliane Bettencourt and family
Net worth: $40.1 billion
Gained $5.6 billion since 2014; jumped 1 spot on the Forbes list
Bettencourt is the heiress to the L'Oreal fortune, and while she's still technically Europe's richest woman, a judge in October 2012 ordered that the elderly billionaire's fortune be placed under the legal control of her daughter and grandsons. The court case over her wealth is ongoing.
#9 Jim C. Walton
Net worth: $40.6 billion
Gained $5.9 billion since 2014; jumped 1 spot on the Forbes list
Another heir to the Walmart fortune, Jim is Chairman and CEO of the family's Arvest Bank, which has branches in Arkansas, Kansas, Oklahoma and Missouri.
#8 Christy R. Walton
Net worth: $41.7 billion
Gained $5 billion since 2014; jumped 1 spot on the Forbes list
Christy Walton inherited her husband John Walton's fortune when he passed away in 2005. John Walton's father was Walmart founder Sam Walton.
#6 (tie) David Koch
Net worth: $42.9 billion
Gained $2.9 billion since 2014; no change on the Forbes list
David, along with brother Charles, is a co-owner and the executive vice president of Koch Industries, one of the largest privately-held companies in the world.
#6 (tie) Charles Koch
Net worth: $42.9 billion
Gained $2.9 billion since 2014; no change on the Forbes list
Charles is a co-owner and executive vice president at Koch Industries along with his younger brother David.
#5 Larry Ellison
Net worth: $54.3 billion
Gained $6.3 billion since 2014; no change on the Forbes list
Ellison, founder of Oracle, did not even graduate from college. He was named entrepreneur of the year by Harvard Business School in 1990.
#4 Amancio Ortega Gaona
Net worth: $64.5 billion
Gained $.5 billion since 2014; dropped 1 spot on the Forbes list
Ortega is the former chairman of Inditex, a conglomerate whose holdings include global fashion retailer Zara.
#3 Warren Buffett
Net worth: $72.7 billion
Gained $14.5 billion since 2014; jumped 1 spot on the Forbes list
Buffett is the CEO of Berkshire Hathaway, as well as the company's primary shareholder. The company had a stellar year, leading to huge gains for Buffett.
#2 Carlos Slim Helu
Net worth: $77.1 billion
Gained $5.1 billion since 2014; no change on the Forbes list
Slim Helu came from humble beginnings. His father was an immigrant shoe maker and Slim built his fortune from almost nothing. And although he has billions now, friends say he wears cheap suits and prefers pen and paper to fancy computers.
#1 Bill Gates
Net worth: $79.2 billion
Gained $3.2 billion since 2014; no change on the Forbes list
Gates is the founder of Microsoft; he dropped out of Harvard after conceiving the company.