Crude Oil ( ) Brent Crude ( ) Natural Gas ( ) S&P 500 ( ) PHLX Oil ( )

Ed Gilligan, the American Express Co. president viewed as a possible successor to Chief Executive Officer Kenneth I. Chenault, died Friday after becoming ill on an overseas flight to New York. He was 55.

Gilligan was returning from a business trip to Tokyo on a corporate jet, which made an emergency landing after he was stricken, according to a person with knowledge of the matter. Efforts to resuscitate him were unsuccessful and the cause of death is undetermined, said the person, who asked not to be identified discussing a personal issue.

“This is deeply painful and frankly unimaginable for all of us who had the great fortune to work with Ed, and benefit from his insights, leadership and enthusiasm,” Chenault said in a letter to the company’s employees. “His contributions have left an indelible imprint on practically every area of our business.”

Gilligan began working as an intern at the firm 35 years ago while a student at New York University, and later spent time in London as a group president overseeing the firm’s international consumer business, according to his LinkedIn profile. He was named vice chairman in 2007 and president in 2013, and oversaw digital initiatives, including a partnership reached last year with car-service firm Uber Technologies Inc.

“He devoted his entire career to this company,” Chenault wrote. “He was a proud husband and father, and his love for his family was evident in all that he did.”

Chelsea Football

Gilligan’s Twitter profile described him as working at the New York-based credit-card issuer and “dreaming of Chelsea football and a good glass of wine, hoping to make a positive impact.” His last tweet, on May 16, referred to a comment about David Letterman’s final show.

“He always liked to be out with clients,” said Gordon Smith, CEO of consumer and community banking at JPMorgan Chase & Co., who worked with Gilligan at AmEx for more than two decades. “He knew everyone, took time to learn people’s names, he knew about their families.”

More from Greece Creditors at G-7 Say Budget Is Red Line as Payment Looms

Gilligan was widely considered a leading candidate to eventually succeed Chenault, according to analysts including Portales Partners’ William Ryan. Chenault, 63, held the title of president before getting the top job in 2001.

First Generation

Edward Patrick Gilligan was born July 13, 1959, in Brooklyn, New York. He was a first generation Irish-American with family from Castlerea, Ireland, on his father’s side, according to a profile in Boardroom Insiders.

He attended the University of Tampa, where he played soccer until a knee injury ended his career. He then enrolled at NYU, where he earned a bachelor’s degree in economics and management in 1982.

Gilligan was group president of global corporate services on 9/11, when the company’s headquarters at the World Financial Center in New York were damaged in the terrorist attack on the World Trade Center Towers across the street.

“We were the fastest growing business in the company going into 2001, and we were the business most decimated,” Gilligan said in a 2014 interview with the Financial Times.

Gilligan is survived by his wife, the former Lisa Sneddon, and their children –- Katie, Meaghan, Kevin and Shane, the company said.