George Soros
Cause: Supporting open societies across more than 60 countries through philanthropic organizations and foundations within the network of his Open Society Institute. The efforts and donations of the Hungarian-born businessman and his network encompass a breadth of philanthropic work, from $100 million for an Internet infrastructure for regional Russian universities to $50 million for the Millennium Promise initiative to eradicate extreme poverty in Africa.
Impact: Soros' network has spent $742 million in the U.S. alone, and Soros, 76, has given away more than $6 billion during his career.