Ellen Johnson Sirleaf

When a bitter civil war tore Liberia apart over a decade ago, Sirleaf helped mend the country, a remarkable feat of leadership that earned her the 2011 Nobel Peace Prize. Last summer, when another menace, the Ebola virus, wreaked havoc, Sirleaf was slower to act a mistake she candidly acknowledged. But after that tepid initial response, she brought the full weight of her government to bear and helped bring the crisis to an end. To be sure, Liberias president, the first female head of state in Africa, has not done enough to tackle the countrys endemic corruption, but few think anyone but Sirleaf could have helped rescue the country the way she did twice.