Viewed for years as a monopolist villain, the Microsoft founder (net worth: $56bn) has reinvented himself as a champion of philanthro-capitalism. His charity, the Bill and Melinda Gates Foundation, is now the largest and most powerful in the world, with assets of more than $37bn, donating more than $2bn annually to disease eradication and poverty reduction.

Along with Warren Buffett, Gates was responsible for the Giving Pledge, a campaign to encourage the US ultra-rich to commit at least half of their fortune to charity. So far, 40 billionaires, including the mayor of New York, Michael Bloomberg, the film director George Lucas and Facebook's Mark Zuckerberg, have signed up. Having revolutionised the world once, it looks like Gates will do so again.

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