OCCUPATION: U.S. Secretary of Energy
PREVIOUS APPEARANCES ON THE TIME 100: 0
PRO: With Obama pushing for renewable energy, the Nobel-winning physicist will most likely be overseeing some of the biggest reforms in history. Just don't make any jokes about a lightbulb going on over his head, unless, of course, said lightbulb is an industry-approved phosphorescent.
CON: He irked Big Coal last December, declaring its mainstay fossil fuel to be his "worst nightmare."