Gene Upshaw, a towering lineman on the football field who went on to win untold millions of dollars for NFL players as their union leader, has died at age 63.

Upshaw had a Hall of Fame career as a guard for the Oakland Raiders — a team that won two of the three Super Bowls it reached during his 15 years in a black and silver jersey. But his work as executive director of the NFL Players Association over a quarter-century was even more important. It changed the business side of the league.

Upshaw died Wednesday night at his home near California’s Lake Tahoe, of pancreatic cancer, the NFL Players Association said yesterday. His wife, Terri, and his sons, Eugene Jr., Justin, and Daniel, were by his side. The president of the NFLPA and Tennessee Titans center, Kevin Mawae, said Upshaw only learned Sunday that he had the disease, after he fell ill and his wife took him to the hospital.

“Gene was a great player. He was an All-Pro. He was a Hall of Famer. If you look at the history of the NFL you’re going to find out that he was one of the most influential people that the league has known. He did so much, not only for the players, but also for the owners, the teams, and the game of pro football,” John Madden, who coached Upshaw when Oakland won its first Super Bowl, said in a statement.

“This is deeper than head of the union passing away, and it’s deeper than an ex-player. This is missing someone that is and was like family. It’s a tough day for all of us.”

Upshaw’s death reverberated throughout the NFL, a shock to owners and players alike, even those who had made him the focal point for their complaints over pension and health benefits for retired players.

As a player, the seven-time Pro Bowler was one of the best ever, elected to the Hall of Fame in 1987, the first time he was eligible.

That also was the year Upshaw led the second players’ strike in five years, a short walkout that led to the embarrassing spectacle of games with replacement players, or “scab football” as it was jokingly called at the time.

By 1989, while the union was pressing in court for a settlement, the league implemented a limited form of freedom, called Plan B. A new, seven-year contract was finally worked out in 1993, bringing in a new age of free agency and salary caps.

That will go down as Upshaw’s legacy because it brought prosperity to both union members and owners, leaving many of today’s players appreciating Upshaw as a labor leader without knowing much about his playing career. The New York Jets player representative, Brandon Moore, was 2 years old when Upshaw retired and said simply: “From what I hear, he was a pretty good player.”

What Upshaw did for Moore and his counterparts is make them money — the salary cap for this season is $116 million and the players are making close to 60% of the 32 teams’ total revenues, as specified in the 2006 labor agreement. The players will be paid $4.5 billion this year, according to owners.

That sum led the owners to opt out in May from the collective bargaining agreement, meaning that if no new deal is reached, there will be an uncapped year in 2010, the season before the contract is expected to expire.

Upshaw, who had often been criticized for his close relationship with the former commissioner, Paul Tagliabue, and the current one, had been talking tougher than usual about upcoming negotiations, vowing that if the cap was ever abolished, he would never accede to a new one.

Upshaw’s death raises a big question mark about negotiations although the union’s executive committee tried to answer it quickly by appointing the union’s most experienced official, Richard Berthelsen, as the interim executive director.

Mr. Berthelsen, the NFLPA’s chief counsel and Upshaw’s top aide, has been involved in labor negotiations for 37 years and is expected to steer the union through the negotiations and then make way for a younger man, probably an ex-player, such as Trace Armstrong or Troy Vincent, two past presidents, or former Minnesota running back, Robert Smith, who has expressed an interest in the job.

But those decisions are in the future. On Wednesday, people from both the sports and labor world rushed to pay tribute to Upshaw, one of the few African-Americans to lead a major union. That there were few indications that Upshaw was ill made his death even harder to take.

“He was and will remain a part of the fabric of our lives and of the Raider mystique and legacy,” the owner and founder of the Raiders, Al Davis, said. “We loved him and he loved us. We will miss him.”