Heckert stepped away from the Broncos after last season after being diagnosed in recent years with amyloidosis, a rare disease that causes a buildup of amyloid proteins in the heart, kidney, liver and other organs. He died Sunday night.
Heckert spent 27 years in the NFL, including the last five in the Broncos' personnel department. He was the teams' director of pro personnel from 2013-16 before becoming senior personnel adviser in 2017.
"Tom was an integral part of our organization and we're all incredibly saddened today," general manager John Elway said in a statement. "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."
Heckert began his NFL career in 1991 as a scout with the Miami Dolphins, who promoted him to assistant director of pro personnel/college scout in 1999 and director of pro personnel in 2000. He was hired by the Eagles as their player personnel director in 2001 and was promoted to vice president of player personnel in 2003.
"We are saddened to learn of Tom Heckert's passing," Eagles owner Jeffrey Lurie said in a statement. "Tom gave everything he had to this organization for nine seasons and played a major role in the construction and success of our team during that time. In addition to being a talented evaluator and respected voice, he was a mentor and friend to so many within our organization and around the league. He will be greatly missed by all who knew and worked with him and our hearts go out to his family during this difficult time."
His father, Tom Sr., worked for more than 20 years as an NFL player personnel executive before retiring in 2007.
"It's easy to see why Tom was widely respected and had so many great relationships across the league," Elway said. "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."
Matt Russell, the Broncos' director of player personnel, worked with Heckert in Philadelphia and Denver.
"Tom was one of the best because he combined exceptional player evaluation skills with his incredible network of connections around the NFL," Russell said. "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."
The Associated Press contributed to this report