Someone whose influence makes the world more peaceful, of course. What makes the world more peaceful? I will list three qualifiers, and people who meet them (Nobel Peace laureates in boldface).
- Activities that lead to significant and long-term decreases in a government's tyranny over its own people, and, if applicable, over conquered nations.
- Ronald Reagan, for leading the West to victory in the Cold War.
- Lech Walesa, for leading the Solidarity movement that led to the collapse of the Polish Communist government.
- Vaclav Havel, for his leadership in the Velvet Revolution in Czechoslovakia, and his role as first president of the Czech Republic.
- George C. Marshall, for his oversight of the American war effort in WWII. (He actually won the award for the Marshall Plan.)
- Dwight D. Eisenhower, for his role as Supreme Allied Commander in Europe during WWII.
- Douglas MacArthur, for his role as Supreme Allied Commander in the Pacific theater during WWII, and for leading the postwar political reformation of Japan.
- King Juan Carlos I of Spain, for overseeing that nation's transition to democracy after the death of Francisco Franco.
- Military efforts that lead to the destruction or significant long-term weakening of a tyrannical revolutionary or terrorist force,
- Alberto Fujimori and the Government of Peru, for waging a successful war against the Communist Shining Path (Sendero Luminoso) insurgency, reducing it to a shadow of its former self. A Shining Path victory in Peru would have led to more Communist uprisings in neighboring countries.
- Diplomatic efforts that lead to long-term peace between once-warring nations.
- Douglas MacArthur. His efforts in Japan led to a strong alliance between our two nations.
- Influence that significantly eases cultural conflict.
- Martin Luther King. Easing of black/white racial tensions had already made a few inroads by the time he came on the scene, but his prominence influenced a broader acceptance of racial tolerance.
- Mother Teresa. Whatever tensions between Christians and Hindus may exist today in India, they would be worse if it weren't for the Macedonian nun's ministry.
Can anyone think of more examples? President Bush doesn't count - it's too early to judge the long-term future of Iraq or Afghanistan, or if al-Qaeda or the Taliban have been permanently crippled as the Sendero Luminoso were.