Occupation: Oil-company CEO
Foster, a lifelong oil engineer, was just named the new CEO of Petrobras, the Brazilian oil company. She becomes its first female CEO and the first woman to run a major oil company. Her promotion couldn't come at a more crucial time: Petrobras is sitting on as much as 100 billion barrels of oil in new offshore reserves, but tapping those deposits will be technically challenging and very expensive. Foster has her work cut out for her.