The richest man on the planet has ambitions to explore life beyond the planet with his space travel company Blue Origin. But it is his 12pc stake in online retail colossus Amazon - where he is CEO - that provides the bulk of Jeff Bezos's (56) vast fortune. Indeed the 4pc of the company that his wife MacKenzie was granted as part of a divorce settlement last year makes her one of the world's richest women. In recent weeks, Bezos, who also owns the Washington Post, sold over $1.7bn of Amazon shares.
Bill Gates (64) was once the world's richest man but now, along with his wife Melinda, heads up the world's largest private charitable foundation. He founded software giant Microsoft in 1975 with Paul Allen and changed the face of home and business computing forever. He owns just 1pc of the company now, having given close to $36bn of the computer company's stock to the Gates Foundation, which is focused on improving global health.
Bernard Arnault (70) has built a fashion and luxury goods empire that includes Louis Vuitton, Moet and Sephora. An appetite for luxury goods amongst consumers in huge markets like China has boosted the worth of his LVMH group. Arnault's father made his money in construction, giving his son the financial firepower to buy Christian Dior in 1985. The French billionaire pledged $220m to help repair Notre Dame cathedral after last year's fire.
Warren Buffett (89) bought his first stock 78 years ago. He now owns more than 60 companies, including Dairy Queen, Duracell and Fruit of the Loom, not to mention a range of minority holdings in some of the world's biggest firms. The so-called Oracle of Omaha still lives in the same Nebraska home he purchased in 1958 for $31,500 and has pledged to give away 99pc of his fortune, much of it to the Bill and Melinda Gates Foundation.
Facebook CEO Mark Zuckerberg (35) said recently that his goal for the next decade was to prioritise being understood over being liked. He has work to do on both fronts with huge criticism over fake news on the world's biggest social network. He started Facebook as a 19-year-old student in Harvard and has pledged to give away 99pc of his wealth. But last year's $5bn fine for Facebook for violating consumers' privacy was probably not part of that plan.
Amancio Ortega (63) is regarded as one of the pioneers of fast fashion and retail giant Zara is a part of Inditex, which he co-founded with his ex-wife Rosalia Mera in 1975, still owning about 60pc. Other brands in his stable include Massimo Dutti and Pull & Bear.
Oracle founder Ellison (75) stepped back from his day-to-day role as CEO of the software firm in 2014 but has kept himself busy since. Apart from serving as both chairman and chief technology officer of Oracle, he has also taken a $1bn bet on Elon Musk's Tesla and sits on the board. He founded Oracle in 1977, revolutionising the tech behind customer relationship management, before acquiring Sun Microsystems for $7.4bn in 2010.
Larry Page (46) co-founded Google in 1998 with fellow Stanford student Sergey Brin. In December he stepped down as CEO of Alphabet, the parent company of Google. His most famous invention is the Google PageRank algorithm, which he developed with Brin and which redefined the internet. Other interests include space exploration company Planetary Resources and a flying car startup.
Like Warren Buffett, Carlos Slim (80) began investing before he was even a teenager and he rose to become Mexico's richest man. The Slim family control America Movil, Latin America's biggest mobile telecom firm and his empire includes Mexican construction firms, retail, property, mining and a minority stake in The New York Times.
Steve Balmer (63) was the CEO of Microsoft between 2000 and 2014, having started out with the firm as it reinvented computing for the masses. Some criticised him for focusing his boundless energies on Microsoft's core Windows product, at a time when companies like Apple and Google were changing the tech world. After leaving Microsoft he bought the NBA's Los Angeles Clippers for $2bn.