2. James Simons

James “Jim” Simons is an American hedge fund manager, a mathematician and a philanthropist. Thanks to his multi-billion-dollar fund, Renaissance Technologies, he ranks No. 82 on the Forbes World’s 2013 Billionaires List, with a net worth of $11.7 billion. The former chairman of Stony Brook University’s math department could easily be the richest Long Islander. But at this point, who’s counting? He still chairs the Stony Brook Foundation, which is dedicated to advancing “the mission and goals” of Stony Brook through philanthropic gifts and grants. He’s also encouraged math literacy (he founded Math for America) and promoted autism research. His Paul Simons Foundation, named for a son killed in a car crash when he was 34, supports education, science and health. His Nathan Simons Foundation, named for a son who drowned in Bali when he was 24, supports health-care work in Nepal. Simons has made a difference putting his fortune to work.