US Department of the Treasury · Public domain

Yellen became the first woman to chair the Federal Reserve, in 2014, and the first to serve as U.S. treasury secretary, seven years later — the only person to have held both roles. An academic economist who spent much of her career at Berkeley, she rose through the Fed's own ranks, from governor in the 1990s to president of the Federal Reserve Bank of San Francisco, before Barack Obama named her vice chair and then chair of the central bank.