Dan Rooney, a sportsman and a statesman whose family has owned the Pittsburgh Steelers since their inception and who served as Ambassador to Ireland in the Obama Administration, died Thursday, the team announced. He was 84.

“Few men have contributed as much to the National Football League as Dan Rooney,” NFL commissioner Roger Goodell said in a statement. “A member of the Pro Football Hall of Fame, he was one of the finest men in the history of our game and it was a privilege to work alongside him for so many years. Dan’s dedication to the game, to the players and coaches, to his beloved Pittsburgh, and to Steelers fans everywhere was unparalleled.”

No details on Rooney’s passing were provided by the Steelers. Rooney did not attend the annual league meetings in Phoenix late last month.

His passing leaves the NFL with one fewer of a dwindling number of men who were instrumental in turning the league and sport from an afterthought to a goliath in the second half of the 20th century.

“Dan Rooney was one of the greatest owners in all of professional sports,” Giants president and CEO John Mara said in a statement. “More than that, he was a great friend who was a man of principle and a role model for any of us privileged to be a part of the NFL. He leaves a legacy on our sport that will last for generations.”

The Rooney and Mara families have always been closely associated through the NFL. Chris Mara, John’s younger brother, married Kathleen Rooney, Dan’s niece. Their daughters, actresses Rooney Mara and Kate Mara, are the great-grandchildren of the founders of both the Giants and Steelers.

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“For those of us who came into this league in the past 30 years, people like Dan Rooney and his family and the Maras, who we are fortunate to partner with, have shown the way, from what the NFL was founded upon to what it is that we all want it to be,” Giants chairman and executive vice president Steve Tisch said in a statement.

Dan Rooney took over the day-to-day running of the Steelers from his father, team founder Art Rooney, in the 1960s. Since then the Steelers have become one of the most successful — and most stable — NFL organizations. They have won six Super Bowls and, since hiring Chuck Noll in 1969, have had only three head coaches.

Rooney was inducted into the Pro Football Hall of Fame in 2000, joining his father. Dan Rooney’s son, Art II, has been the Steelers’ president since 2003, when Dan Rooney became chairman.

In Pittsburgh, he will be remembered for bringing championship football, and one of the NFL’s great dynasties, to the city. Outside western Pennsylvania, though, Rooney’s most lasting NFL legacy likely will be the Rooney Rule, which the NFL adopted in 2003. It requires teams to interview minority candidates for head coaching and senior front office jobs.

“A voice of reason on a wide range of topics, including diversity and labor relations, Dan always had the league’s best interests at heart,” Goodell said. “For my part, Dan’s friendship and counsel were both inspiring and irreplaceable.”

“Dan Rooney was an extraordinary man of faith, conviction, reason and peace,” former NFL commissioner Paul Tagliabue said in a statement. “He loved his family, his Steelers and his Pittsburgh . . . Dan was my mentor, role model, indispensable supporter and great friend during five decades. In the NFL, he is irreplaceable.”

Rooney also served as the United States Ambassador to Ireland from 2009 to 2012 under President Barack Obama, who called him “a championship-caliber good man.”

“Dan Rooney was a great friend of mine,” Obama said in a statement, “but more importantly, he was a great friend to the people of Pittsburgh, a model citizen, and someone who represented the United States with dignity and grace on the world stage.”