AGE 89: Queen Elizabeth II

Head of State of the UK and 15 other Commonwealth realms

What makes her powerful: Since her reign began at the age of 25, Queen Elizabeth II has wielded a "soft power," asserting her influence with the prime minister to indirectly affect political change (setting the prime minister's plan for an EU membership referendum in motion, for example). She's the world's oldest-reigning monarch, and the UK's longest-reigning head of state. The Queen is now twice a great-grandmother, when grandson Prince William and his wife Duchess Kate gave birth to a baby girl, Charlotte Elizabeth Diana, just a few months ago.