No. 1: Bill Gates
Age: 58
Country: United States

No. 1 should come as little surprise: though Microsoft MSFT +0.34% isn’t the behemoth it was back in the ’90s, Bill Gates still remains the richest person in the world–a title he’s held since 1994. In recent years, the chairman of the software company has set boisterous standards for efforts to eradicate a variety of the most dire diseases, from polio to HIV. Thanks to his strong ties with billionaire comrades like Carlos Slim and Michael Bloomberg, the Bill & Melinda Gates Foundation has secured up to $335 million in pledges.

No. 2: Larry Page and Sergey Brin
Ages: 40
Country: United States

Google cofounders Larry Page and Sergey Brin both take the No. 2 spot by Forbes. Combined, the two have an estimated net worth just shy of $50 billion. Page, who is tasked with running Silicon Valley’s most celebrated company, is a huge spender when it comes to research and development.

In September, he announced Google’s new investment in Calico, a company created to take on the challenges of age-associated diseases. Brin oversees Google X, a division that has greeted with world with breakthrough technologies (driverless car, Google Glass). Earlier this year, he and Anne Wojcicki donated $52 million to the Michael J. Fox Foundation to fight Parkinson’s disease.

No. 3: Mark Zuckerberg
Age: 29
Country: United States

At 29, Mark Zuckerberg (No. 3 by Forbes) is the youngest entrepreneur to make the list. The Facebook CEO has expanded his influence beyond the social network by advocating for immigration reform and technology education. Last year, he donated $10 million shares of his company to the Silicon Valley Community Foundation.

No. 4: Michael Bloomberg
Age: 71
Country: United States

Michael Rubens Bloomberg, an American business magnate, politician and philanthropist is on No. 4 spot by Forbes. He is the 108th and current Mayor of New York City, having served three consecutive terms since his first election in 2001. With a net worth of $31 billion, he is the seventh-richest person in the United States and the thirteenth-wealthiest in the world.He is the founder and 88% owner of Bloomberg L.P., the global financial data and media company notable for its Bloomberg Terminal.

No. 5: Masayoshi Son
Age: 56
Country: Japan

Masayoshi Son, a Japanese businessman and the founder and current chief executive officer of SoftBank, the chief executive officer of SoftBank Mobile, and current chairman of Sprint Corporation is at No. 5 by Forbes. According to Forbes magazine, his net worth is $8.1 billion as of 2011 and he is the second richest man in Japan, despite having the distinction of losing the most money in history (approximately $70 billion during the dot com crash of 2000).Forbes also describes him as a philanthropist.

BY Rakesh Jha