Bill Gates (was born October 28, 1955) is an American entrepreneur and social activist, philanthropist, co-founder (with Paul Allen) and former largest shareholder of Microsoft. Until June 2008, he was the head of the company; after leaving office, he remained as its non-executive chairman of the board of directors. He is also co-chairman of the Bill & Melinda Gates Foundation, member of the board of directors of Berkshire Hathaway, CEO of Cascade investment.