Tom Heckert, who spent the 2001 through 2009 seasons with the Eagles' scouting department and served as Andy Reid's general manager from 2006 through 2009, died overnight, the Broncos announced Monday.
Heckert had been battling a condition known as amyloidosis, in which an abnormal number of proteins can build up in tissue.
He was only 51.
"Tom was an integral part of the front office that took the Eagles to five championship games in eight years," said Joe Banner, who was the Eagles' team president during Heckert's entire stay in Philadelphia.
"He was as committed as anyone to focus on what was good for the Eagles and never cared about who got credit. He will be deeply missed by all who had the pleasure to know him."
Heckert's last NFL job was as senior personnel adviser with the Broncos, but he stepped down from that position earlier this summer because of his health.
During his years as GM here, the Eagles drafted all-time great Eagles such as DeSean Jackson, LeSean McCoy, Jeremy Maclin, Brent Celek and Jason Avant.
"It's easy to see why Tom was widely respected and had so many great relationships across the league," said Broncos president John Elway, the Hall of Fame quarterback.
"I'll always be grateful for how he helped me transition into this position. My prayers go out to Tom's family, friends and everyone he worked with during his career."
Heckert spent 10 years in the Dolphins' scouting department, working under his father for most of that period, before joining the Eagles in 2001 as director of pro personnel.
He was promoted to vice president of pro personnel in 2003 and became general manager in 2006.
Heckert went to the Browns as general manager in 2010 and the Broncos in 2013.
Heckert was Reid's top personnel adviser during most of his stay in Philadelphia, and he was instrumental in helping build the roster that went to five NFC Championship Games and a Super Bowl in an eight-year period.
He finished his career with the Broncos, where he helped build teams that went to the playoffs in 2013, 2014 and 2015, reached two Super Bowls and won Super Bowl 50 after the 2015 season.
"Tom was an integral part of our organization and we're all incredibly saddened today," Elway said.
"With his many years of experience and time as a GM, Tom was a tremendous resource and a key member of our team. He was a very good evaluator. He had an eye for talent, and we always trusted his voice."
In 2006 with the Eagles, Heckert hired a regional scout named Matt Russell, who was promoted in 2008 to regional scout and is now the Broncos' highly regarded director of player personnel.
"Tom hired me in Philadelphia and was a beloved friend for many years," Russell said.
"The biggest thing with Tom was his loyalty, how he cared about his friends and how good he was at his job. Tom was one of the best because he combined exceptional player evaluation skills with his incredible network of connections around the NFL.
"Those relationships he formed are a testament to how well he treated everyone. Tom was a loyal friend and my heart goes out to his family."
