Some of the most popular Pro Football Hall of Famers are threatening not to return to Canton for the annual enshrinement or for the NFL's centennial celebration planned for 2020 in Canton unless they receive health care benefits and a salary from the National Football League.

The letter — sent to NFL Commissioner Roger Goodell, NFL Players Association Executive Director DeMaurice Smith and David Baker, president of the Pro Football Hall of Fame — was sent by Eric Dickerson, chairman of a newly formed Hall of Fame Board.

ESPN obtained a copy of the letter, which questions Goodell's annual salary, reported to be about $40 million, and the $1 billion Johnson Controls Hall of Fame Village development in Canton. Hall of Fame Village is a mixed-use development in Canton being mostly financed by investors. The NFL does not have a financial stake in Hall of Fame Village.

"Meanwhile, many of us Hall of Fame players can't walk and many can't sleep at night," ESPN reported the letter as stating. "More than a few of us don't even know who or where we are. Our long careers left us especially vulnerable to the dangers of this violent sport, especially those intentionally hidden from us. Commissioner Goodell, there are better uses for that money."

The board includes Marcus Allen, Mel Blount, Derrick Brooks, Jim Brown, Earl Campbell, Richard Dent, Carl Eller, Marshall Faulk, Mike Haynes, Rickey Jackson, Ronnie Lott, Curtis Martin, Joe Namath, John Randle, Jerry Rice, Deion Sanders, Bruce Smith, Jackie Smith, Lawrence Taylor and Kurt Warner. Reggie White's widow Sarah, also is on the board. Brown, the former Cleveland Browns great running back, was scheduled to make an appearance in Canton last week, but did not.

The Hall of Fame has increased appearances for Hall of Famers and fees for those players since Baker's arrival in Canton. The Hall of Fame, while working closely with the NFL, is not a part of the league and operates independent of the league's annual revenue.

Messages seeking comment were left with the NFL and the Hall of Fame.

Hall of Famer Joe DeLamielleure is an outspoken critic of the NFL and the players union. He said the Hall of Fame is caught in the middle.

"I've never missed an induction since I was enshrined in 2003 — I literally walked there one year from Buffalo — but it's a tough situation," DeLamielleure said. "A lot of guys are not in a good position financially and we've been asking the league for help forever. Just help take care of the pre-’93 guys ... and there's never been a response. This has accomplished something. There's attention now."

DeLamielleure said he is paid $1,247 a month from his NFL pension and $1,140 from the league's Legacy Fund. He said he has worked with John Riggins on pension parity. There is a nonprofit group — FAIR (Fairness for Athletes In Retirement) asking the NFL for pension parity for pre-1993 players. The website outlines some former players' issues and puts together a solution of pension parity.

"That's 13 seasons in the NFL and I make less than $29,000 a year," DeLamielleure said. "And I'm lucky. I never had a surgery. ... I don't blame the Hall of Fame. I blame the league and the union. We have a corrupt union.

"It's unbelievable all the money that's being made and we can't take care of all former players, and particularly Hall of Famers. If you're a Hall of Famer, at least you should be taken care of. There is so much money being made right now you can literally quit at halftime. That's how much money guys make. Give us pension parity and we don't even need health care."

According to ESPN, the letter states:

"The time has come for us to be treated as part of a game we've given so much to. Until our demands are met, the Hall of Famers will not attend the annual induction ceremony in Canton. It's well-known that the NFL is celebrating its 100th anniversary in 2020, and while we are proud of our role in building this league, we don't believe 100 years of player exploitation is something to celebrate. As we approach this momentous date, we challenge the NFL to honor its past by helping retired players instead of exploiting their images for marketing purposes.

"People know us from our highlight reels. They see us honored and mythologized before games and at halftime, and it would be reasonable if they thought life was good for us. But on balance, it's not. As a group we are struggling with severe health and financial problems. To build this game, we sacrificed our bodies. In many cases, and despite the fact that we were led to believe otherwise, we sacrificed our minds. We believe we deserve more. We write to demand two things: Health insurance and annual salary for all Hall of Famers that includes a share of league revenue."

The new board's letter points out the league generated $14 billion and members of the board were "integral to the creation of the modern NFL ... . But when the league enshrined us as the greatest ever to play America's most popular sport, they gave us a gold jacket, a bust and a ring — and that was it."

Dave Robinson, enshrined in 2013, said he did not have a chance to see the letter and declined to comment on the specifics of it.

"But I see where the frustration is coming from," Robinson said. "What the guys went through in the early days to make the league what it is today — a lot of people feel we have not been adequately rewarded."

Robinson acknowledged the Hall has increased speaking opportunities for former greats but, "it's mainly marquee players."

League revenues are totaled from many sources, including ticket sales, media contracts and sponsorships among the 32 independently owned franchises. The NFL does not enshrine players or choose which players are elected to the Hall.

"People say you got to live a dream playing in the NFL. Yeah, but that doesn't mean our families should live a nightmare," DeLamielleure said. "I love the Hall. I'm as blue collar as it gets. I grew up in Detroit, played in Buffalo and Cleveland. ... I didn't plan to get rich off the NFL, but I also didn't plan on making people multi-millionaires off our backs and us get nothing."