The banking industry lost one of its most prominent women a year ago with the death of Terri Dial. As a leader, a mentor and a C-suite veteran in a male-dominated business, she left a void that has yet to be filled.

Dial spent four decades helping to run some of the country's biggest banks, including Wells Fargo (WFC) and Citigroup (NYSE:C). Her death from pancreatic cancer at age 62 widened a persistent gap in the industry's top ranks, where women are still struggling to find equal footing — or, once there, to keep it.

"Terri had a pretty substantial impact on the industry — she mentored so many women, and I'm not sure who takes her place in that regard. There's a big hole there in the last two or three years," says Lynn Carter, who retired in late 2011 as the president of Capital One (COF).

Carter, who worked for Dial at Wells Fargo and became one of her closest friends, last month went to Miami to attend a memorial organized by Dial's husband, Brian Burry. About 25 of Dial's friends, family and former colleagues traveled to the event, which was held on Feb. 28, the first anniversary of her death. Ahead of the memorial, several friends shared their memories of Dial and reflected about how the industry has changed without her.

"There are very few women who have done as much as Terri to further women's careers," Deborah McWhinney, chief operating officer of Citigroup's global enterprise payments unit, said in an email.

Other women hired and mentored by Dial called her legacy immeasurable.

"Any time you're working in an industry and there's an iconic person — and she really was — who you can look up to and say, 'Wow, she's done it,' people rally around it," says Margaret Kane, a consultant who started her banking career when Dial hired her at Wells Fargo in 1988. "That's her lasting impact."

Dial's death marked the start of a difficult year for senior women in banking, whose numbers are still relatively few and far between.

At Citigroup, where Dial spent two years trying to revamp the troubled consumer bank before stepping down, all 13 of the executives reporting directly to Chief Executive Michael Corbat are men. (His chief of staff is a woman.) Dial's eventual successor, Cece Stewart, is the only woman on Corbat's operating committee, and is reportedly under pressure to improve results.

There are some signs of progress, at least in the lower ranks; Citigroup got top marks for corporate diversity in a Calvert International survey released last week. And the industry can boast a few high-ranking women executives: JPMorgan Chase (JPM) recently promoted Marianne Lake to chief financial officer (although chief investment officer Ina Drew left last year after the London Whale trading losses). Irene Dorner runs HSBC's U.S. businesses, and this year was named to its top management board, while KeyCorp's (KEY) Beth Mooney in 2011 became the first woman CEO of a top-20 U.S. bank.

But at the largest U.S. banks, visible and powerful women have become most notable for their departures. Few current executives have achieved the same prominence of Dial or Sallie Krawcheck, who was pushed out of Bank of America (BAC) in 2011. Several people interviewed for this article also compared Dial and her influence to Barbara Desoer, B of A's well-respected former head of mortgages, who retired last year after her role was gradually diminished.

"The industry is going through immense change, and I think that sense of uncertainty is probably really challenging, and I think having a void with someone like Terri's talent at a time like this is pretty big," says Carter. "I don't see a lot of women in the executive suites these days, so I hope someone's paying attention to it."

Dial's legacy goes beyond her role as a mentor to other women. Her obituaries last year made much of her energy, her determination and her "Human Cyclone" nickname. They spent less time on her contributions to the banking industry, starting as a teller at Wells Fargo. Almost three decades later, she retired as head of its California operations, and later joined the U.K.'s Lloyds TSB Group as the first American head of consumer banking. In 2008 Citigroup hired her as CEO of its North American consumer banking unit; in 2009, American Banker named her No. 10 on its annual list of the industry's most powerful "Women to Watch."

Over the course of that career, Dial reshaped the model for retail banking and small-business lending, her former colleagues said.

"She was always an incredible innovator, always pushing for the next thing that would help to transform the business … as the notion of a retail bank was just emerging," says Kane. "She was really the critical innovator in the industry when it came to Saturday banking, in-store banking, longer hours. Those things really happened on her watch — figuring out how we can offer this to customers while lowering the cost" to the bank.

Dial also understood "the delicate balance between profits, customers and employees," Kane says. "If you're a leader in banking, you have to be attuned to all of those elements."

Pat Callahan, Wells Fargo's current chief administrative officer, said via a spokeswoman's email that Dial's "contributions to not only Wells Fargo but to the entire banking industry have helped shape retail banking as a customer and service focused business."

Dial also built up Wells Fargo's small-business lending operations at a time when few financial companies had figured out how to make that sort of business profitable, says retired Wells executive Mike James.

"The challenge of small-business lending was always how to make money, because the loans were so small and you had to put in so many resources," he says, adding that Dial helped solve that problem by championing the adoption of credit-scoring for small-business customers. "She was incredibly smart, she was very forward-thinking, she was willing to try new things and very much into testing things and learning."

James, who retired last year as a group executive vice president for Wells Fargo's diversified products group, climbed the company's ranks with Dial and worked for her at one point. He says Dial's "very, very tough but fair" leadership style was similar to that of CEO John Stumpf and his predecessor Richard Kovacevich.

"She would take a lot of input from people, she would debate things, but she was a dictator. Once she made up her mind, that was the way we would do things," James says. "Most of the really good managers I've worked for, they were good dictators."

Dial's fearlessness was legend. She spent her vacations traveling around the world, and at work, "there wasn't anything she was afraid to do or take on. She took on some of the lousiest jobs in the commercial bank," says Jim Hulihan, Jr., also a former Wells Fargo colleague.

"If you were a guy, you always had to compete against her. She wasn't someone you could slough off," says Hulihan, who went on to run Bank of America's commercial cards business, before eventually retiring. "Terri was one of the first to really break through the [gender] barriers and get bigger and better jobs."

Burry, who met Dial at Wells Fargo in 1977 and was married to her for more than 31 years, has endowed a scholarship in her name at Northwestern University. (Citigroup and several of the memorial's attendees have contributed to the scholarship, he said.) When Dial started at the university in 1967, she considered it to be the best school that would admit women, according to Burry.

"Education was a huge part of Terri's life … she believed that her NU degree got her going," he recalled in a phone conversation.

He called the memorial a success and said it drew friends from as far away as California and Scotland to Miami. The guests ended the day with "pizza, beer and wine and a lot of Terri stories," Burry added in an email this month. "I think she would have been pleased."

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