Gene Upshaw, who made his name as an offensive lineman for the Raiders before becoming the executive director of the NFL Players Association, has died. The Hall of Famer, 63, had been diagnosed with pancreatic cancer just four days ago, and according to the NFL PLAYERS ASSOCIATION web site, he passed away with his family by his side.

As NFL.COM notes, Upshaw had been involved with labor issues for more than 30 years, first as a player, and then as the head of the NFLPA. His tenure was not without controversy, however.

In 2006, he was accused of neglecting former players who had retired with few, if any, benefits, and Ravens kicker Matt Stover had mounted a campaign to oust Upshaw from his executive director position. But he also had a long list of accomplishments, including the most recent collective bargaining agreement.

As for who might succeed Upshaw, PRO FOOTBALL TALK speculates:

Possibilities include NFLPA General Counsel Richard Berthelsen, and NFLPA outside counsel Jeffrey Kessler. Another possibility (albeit, in our view, remote) would be agent Tom Condon, who represented Upshaw and previously served as NFLPA President.

Upshaw is survived by his wife, Terri, and sons, Justin, Daniel and Eugene Jr.