The NEWSWEEK 50: Margaret Chan, World Health Org.

With the global spread of diseases more of a threat than ever, Chan represents the world's first line of defense. The well-liked leader of the WHO is known for her interest in women's issues and African health, but her background is in emerging diseases. As Hong Kong's director of health, she handled the avian flu and SARS, ultimately stopping SARS by culling the city's 1.5 million poultry population. One admirer calls her "the James Brown of global health" for her work ethic. In her circles, she's certainly a rock star.