The National Football League agreed to a $765 million settlement with the more than 4,500 former players who filed concussion-related lawsuits Thursday, effectively ending the biggest legal threat to the country’s most popular sports league.

For two years, scores of players filed suit against the NFL, claiming the league misled them on the sport’s dangers, a controversy that highlighted its violent past and cast uncertainty on its future. The settlement unveiled Thursday would fund medical exams and research as well as provide compensation for former players who are suffering from the debilitating effects of concussions.

“This is a historic agreement, one that will make sure that former NFL players who need and deserve compensation will receive it and that will promote safety for players at all levels of football,” said Layne Phillips, the court-appointed mediator and a former U.S. District judge.

The proposed settlement, which must be approved by District Court Judge Anita B. Brody, is a surprisingly quick resolution to a case that involves former players and their families, who charged that the NFL concealed the long-term dangers of repeated hits to the head and the resulting concussions and chronic traumatic encephalopathy (CTE). The league countered that it had issued warnings based on available medical research and that player safety is governed by the collective bargaining agreement with the NFL Players Association.

Under terms of the proposed settlement, the NFL does not admit to any liability or concede that injuries suffered by the plaintiffs were caused by football. Roughly half of the settlement will be paid out over the first three years, with the balance spread over the following 17.

“I believe we got everything we could possibly get out of the NFL in this litigation,” lead plaintiffs’ attorney Christopher Seeger said.

Still, much of the initial reaction in the both the sports and legal worlds centered on the terms and whether the plaintiffs were able to squeeze enough out of a league that generates more than $9 billion in annual revenues. An attorney for NFL insurer Alterra America told the New York State Supreme Court earlier this year that the litigation could have ultimately cost the league more than $2.5 billion.

“Some people I’m sure will say this is petty change, peanuts,” said Arthur Miller, a law professor at New York University. “Some people will say this was a $2 billion case. And maybe it was. But the risks of litigating these kinds of highly complex cases with issues like causation, the burdens of proof and the amount of time litigation would have taken — there are many people in this group who can’t wait five or eight more years.”

While the string of lawsuits included more than 4,500 former players — ranging from Pro Football Hall of Famers to fringe players who barely set foot on the field — the proposed settlement would actually encompass all NFL retirees, which number approximately 16,000.

“Commissioner [Roger] Goodell and every owner gave the legal team the same direction: Do the right thing for the game and for the men who played it,” said Jeff Pash, the NFL’s executive vice president. “We thought it was critical to get more help to players and families who deserve it rather than spend many years and millions of dollars on litigation.”

Payouts will vary with former players suffering from ALS capped at $5 million; those suffering from CTE, a degenerative brain disease associated with head trauma in athletes, at $4 million; and those suffering from dementia at $3 million.

“If anybody could go out there and find a deal of this size with those kind of payouts, I’d be really surprised,” Seeger said.

The settlement represents only a small fraction of NFL revenues, and it’s still less than the Forbes valuation of the NFL’s least valuable team, the Oakland Raiders ($825 million). Retired NFL center Kevin Mawae, a former NFL Players Association president who is not part of the litigation, took issue with the dollar amount, comparing it with the billions the league stands to make in the next 20 years.

“NFL concussion lawsuit net outcome? Big loss for the players now and the future!” Mawae wrote on Twitter.

Some legal observers agree the plaintiffs could have sought more money, but there were risks and costs involved. A drawn-out case might have covered several years.

“I think this is exactly what both sides needed,” said Miller, chairman of the NYU Sports & Society Program. “To litigate this further would’ve caused delays and further expenses. The NFL knows it has a problem. The retired players in some cases are in desperate condition. Some have died. This is a civilized way of resolving a problem both sides had.”

Former Atlanta Falcons safety Ray Easterling, who filed the first lawsuit two years ago and was the lead plaintiff, committed suicide in April 2012. Among the high-profile former players whose names were attached to the lawsuit were Jim McMahon, Tony Dorsett, Clinton Portis, Mark Rypien and Art Monk. The family of Junior Seau, the former San Diego Chargers linebacker who committed suicide in May 2012, also had joined the suit.

Helmet manufacturer Riddell is also a defendant in the litigation but is not part of the proposed settlement.

Any player who has retired by the date the settlement is eventually approved — attorneys estimate 30 to 60 days from now — is included under terms of the agreement, which means all active players would be excluded. The deal calls for $75 million to go toward baseline medical exams. A settlement administrator will use the results of those tests to determine treatment and exact compensation.

“I don’t know that a lot of us are going to make significant money off of this, and that was never the intent,” said Rypien, a former Washington Redskins quarterback. “But what we wanted was to know that if there was a need that would arise, then the cost of that care would be taken care of and that our health will be monitored.”

Kevin Turner, a former running back who is suffering from amyotrophic lateral sclerosis (ALS), championed the settlement during a conference call.

“Today is so important for those who are hurting, those who are struggling,” Turner said. “This will bring help for them today. The compensation provided in this settlement will lift a huge burden off men who are suffering right now. Both them and their families, of course. It will give them the peace of mind to have the best quality of life they’re able to have.”

The timing of the resolution was also beneficial for the NFL, which will stage its regular season opener Thursday when the Baltimore Ravens play at the Denver Broncos.

“This removes an enormous cloud,” said Carl Tobias, a law professor at the University of Richmond. “They had huge incentive to settle and put this behind them before the season starts.”

Mark Maske and Mike Jones contributed to this report.