Age: 62
Occupation: Secretary of the Department of Health and Human Services
Previous TIME 100 appearances: 0
The former governor of Kansas holds the keys to whether the Democrats' sweeping health care reform law is implemented smoothly or whether it's a morass of misguided regulations and unintended consequences. With power over a budget larger than the Pentagon's, Sebelius will need to fight hard to stand up to Republicans and interest groups as they try to whittle the Affordable Care Act down to a nub.