‘They should have let Bear Stearns fail,” Sheila Bair said.

It was midmorning on a crisp June day, and Bair, the 57-year-old outgoing chairwoman of the Federal Deposit Insurance Corporation — the federal agency that insures bank deposits and winds down failing banks — was sitting on a couch, sipping a Starbucks latte. We were in the first hour of several lengthy on-the-record interviews. She seemed ever-so-slightly nervous.

Long viewed as a bureaucratic backwater, the F.D.I.C. has had a tumultuous five years while being transformed under Bair’s stewardship. Not long after she took charge in June 2006, Bair began sounding the alarm about the dangers posed by the explosive growth of subprime mortgages, which she feared would not only ravage neighborhoods when homeowners began to default — as they inevitably did — but also wreak havoc on the banking system. The F.D.I.C. was the only bank regulator in Washington to do so. During the financial crisis of 2008, Bair insisted that she and her agency have a seat at the table, where she worked — and fought — with Henry Paulson, then the treasury secretary, and Timothy Geithner, the president of the New York Federal Reserve, as they tried to cobble together solutions that would keep the financial system from going over a cliff. She and the F.D.I.C. managed a number of huge failing institutions during the crisis, including IndyMac, Wachovia and Washington Mutual. She was a key player in shaping the Dodd-Frank reform law, especially the part that seeks to forestall future bailouts. Since the law passed, she has made an immense effort to convince Wall Street and the country that the nation’s giant banks — the same ones that required bailouts in 2008 and became known as “too big to fail” institutions — will never again be bailed out, thanks in part to new powers at the F.D.I.C. Just a few months ago, she went so far as to send a letter to Standard & Poor’s, the credit-ratings agency, suggesting that its ratings of the big banks were too high because they reflected an expectation of government support. If a too-big-to-fail bank got into trouble, she wrote, the F.D.I.C. would wind it down, not bail it out.

As an observer of the financial crisis and its aftermath, I have frankly admired most of what she tried to do. She was tough-minded and straightforward. On financial matters, she seemed to have better political instincts than Obama’s Treasury Department, which of course is now headed by Geithner. She favored “market discipline” — meaning shareholders and debt holders would take losses ahead of depositors and taxpayers — over bailouts, which she abhorred. She didn’t spend a lot of time fretting over bank profitability; if banks had to become less profitable, postcrisis, in order to reduce the threat they posed to the system, so be it. (“Our job is to protect bank customers, not banks,” she told me.) And she was a fierce, and often lonely, proponent of widespread mortgage modification, for reasons both compassionate (to help struggling homeowners stay in their homes) and economic (fewer foreclosures would help the troubled housing market recover more quickly).

I thought something else as well: with her five-year term as F.D.I.C. chairwoman drawing to a close — her last day was July 8 — she never really got her due. The rap on her was always that she was “difficult” and “not a team player.” There were times, in Congressional testimony, when she disagreed with her fellow regulators even though they were sitting right next to her. Her policy disputes with other regulators were legion; in leaked accounts, Bair was invariably portrayed as the problem. In “Too Big to Fail,” for instance, the behind-the-scenes account of the financial crisis by the New York Times business columnist Andrew Ross Sorkin, Bair is described as one of Geithner’s “least favorite people in government.” As Paulson, Geithner and the Federal Reserve chairman, Ben Bernanke, raced to bail out banks and companies like A.I.G., Bair resisted, fearing that they were being overly generous by putting the interests of bondholders over those of taxpayers. I couldn’t help recalling that the last female financial regulator to be labeled difficult was Brooksley Born, the head of the Commodity Futures Trading Commission in the mid-1990s. Fearful that derivatives were becoming a threat to the financial system, Born wanted to regulate them but was stiff-armed by Alan Greenspan and Robert Rubin.