A billionaire is a person with a net worth of at least one billion units of a given currency, usually of a major currency such as the United States dollar, euro, or pound sterling. The American business magazine Forbes produces a global list of known U.S. dollar billionaires every year and updates an Internet version of this list in real time. The American oil magnate John D. Rockefeller became the world's first confirmed U.S. dollar billionaire in 1916, and still holds the title of history's second wealthiest individual.
The Forbes 400 or 400 Richest Americans is a list published by Forbes magazine of the wealthiest 400 American citizens who own assets in the U.S., ranked by net worth. The 400 was started by Malcolm Forbes in 1982 and the list is published annually around September. Peter W. Bernstein and Annalyn Swan describe the Forbes 400 as capturing "a period of extraordinary individual and entrepreneurial energy, a time unlike the extended postwar years, from 1945 to 1982, when American society emphasized the power of corporations." Bernstein and Swan also describe it as representing "a powerful argument – and sometimes a dream – about the social value of wealth in contemporary America."
Black billionaires are individuals who are of predominantly African ancestry with a net worth of at least US$1 billion.
The Giving Pledge is a campaign to encourage extremely wealthy people to contribute a majority of their wealth to philanthropic causes. As of December 2021, the pledge has 231 signatories from 28 countries. Most of the signatories of the pledge are billionaires, and as of 2016, their pledges are estimated to total US$600 billion.
The World's Billionaires is an annual ranking by documented net worth of the wealthiest billionaires in the world, compiled and published in March annually by the American business magazine Forbes. The list was first published in March 1987. The total net worth of each individual on the list is estimated and is cited in United States dollars, based on their documented assets and accounting for debt and other factors. Royalty and dictators whose wealth comes from their positions are excluded from these lists. This ranking is an index of the wealthiest documented individuals, excluding any ranking of those with wealth that is not able to be completely ascertained.
Switzerland 
Australia 
South Africa 
Italy 
Germany