Prince Alwaleed bin Talal al-Saud

Cause: Fostering a better understanding of Islam. With his $20 billion fortune, he has endowed American studies at Middle Eastern universities, given $40 million to underwrite Islamic studies at Harvard and Georgetown and helped fund the construction of an Islamic wing at the Louvre in Paris. He has also given nearly $25 million to tsunami and earthquake victims.

Impact: Alwaleed has helped raise the profile of Islamic history and culture around the world.