Gates founded software giant Microsoft in 1975 with Paul Allen and changed the face of home and business computing forever. He has topped the Forbes list of the 400 richest Americans for 24 years and, with wife Melinda, chairs the world's largest private charitable foundation. Forbes' real-time tracking of his wealth shows it has since surpassed the $90bn mark, helped no doubt by the launch of a new energy fund in 2016.
The so-called Oracle of Omaha still lives in the same Omaha, Nebraska home he purchased in 1958 for $31,500 and, to date, has given away $32bn of his huge fortune. His Berkshire Hathaway conglomerate - which owns at least 60 companies - continues to boom with its share price topping $300,000 in December. The growth of Buffett's wealth has been even more rapid than that of his good friend Bill Gates over the past year.
Amazon is finding a way into every part of our lives and its founder's wealth has grown so much since the official Forbes 2017 listing - to over $100bn - that he is now likely to be the richest person on the planet. Apart from his 17pc stake in the online retailer he founded in a Seattle garage in 1994, Bezos also owns The Washington Post and space travel company Blue Origin.
Europe's richest man cofounded Inditex - the parent of fashion retail giant Zara - with his ex-wife Rosalia Mera in 1975. The Spaniard enjoys dividends of more than $400m and has invested wisely in property in Europe and the US.
Facebook's share price has more than quadrupled since it went public in 2012 and with it, the wealth of its founder Mark Zuckerberg. The 2017 Forbes listing of $56bn is long since out of date and Zuckerberg, who started the social network in 2004 as a student before dropping out of Harvard, has since added at least $20bn to his worth.
The Slim family controls America Movil, Latin America's biggest mobile telecom firm, making Carlos Mexico's richest man. His empire now includes Mexican construction firms, retail, property, mining and a minority stake in The New York Times.
Oracle founder Ellison stepped back from his day-to-day role as CEO of the software firm in 2014, although he still serves as both chairman and chief technology officer. The company revolutionised the technology behind customer relationship management after it was founded in 1977 but in more recent times, it has moved into cloud computing and hardware following its $7.4bn acquisition of Sun Microsystems in 2010.
Chairman and CEO of Koch Industries Charles is these days perhaps best known as the rich donor behind a range of right-wing US foundations, including the Cato Institute and the Heritage Foundation. But his $100bn private company, founded by his father Fred in 1940 and led by Charles since 1967, owns a dizzying array of assets including companies producing pipelines, chemicals, paper cups, towels and carpets.
The second of the famous Kansas Koch brothers, David owns a 42pc stake in Koch Industries, as does brother, Charles, after the pair bought out their other two brothers' shares in 1983. David is a well-known philanthropist and ran for vice-president on a Libertarian ticket in 1980, winning just 1pc of the vote.
The co-founder of the Bloomberg financial information and media empire retains an 88pc stake in the company. Bloomberg served three terms as an independent mayor of New York City but, to date, never bowed to intense speculation that he would take a stab at a presidential run. He has been a major donor to liberal causes such as gun control and climate change.
Rich List 2018
As 2018 gets under way, the economy is humming and the country is making its way back to full employment. With no let-up in the flow of foreign direct investment and with a chronic shortage in housing supply to be addressed, there will be no shortage of potential entrants to Ireland's property market as it once again becomes the only show in town.