He also played for the San Diego Chargers in 1972 and finished his 10-year career with 331 catches for 5,236 yards and 38 touchdowns.
Mr. Mackey's efforts after his playing days were just as important as his performance on the field. An NFL labor agreement ratified in 2006 includes the "88 Plan," named for Mr. Mackey's number, 88. It provides up to $88,000 a year for nursing care or day care for ex-players with dementia or Alzheimer's disease, or $50,000 for home care.
"John Mackey is still our leader. As the president of the NFLPA, he led the fight for fairness with a brilliance and with ferocious drive," said DeMaurice Smith, the union's executive director.
The health care of former players has become a prominent issue in the negotiations for a new collective bargaining agreement. The NFL's players have been locked out since March.
"John Mackey was one of the great leaders in NFL history, on and off the field," commissioner Roger Goodell said. "He was a Hall of Fame player who redefined the tight end position. He was a courageous advocate for his fellow NFL players as head of the NFL Players Association. . . . He never stopped fighting the good fight."
Mr. Mackey was drafted in 1963 out of Syracuse - by the NFL's Baltimore Colts in the second round and the AFL's New York Jets in the fifth round.
He wound up playing for the Colts just as the passing game was taking on a major role in pro football. His size, speed, and ability to catch the ball while also blocking in the running game made him the prototype for future generations of tight ends.
"John revolutionized the tight end position during his Hall of Fame career, and he laid the foundation on and off the field for modern NFL players," said Ravens general manager Ozzie Newsome, a fellow Hall of Fame tight end.
Mr. Mackey caught 35 passes for 726 yards as a rookie in 1963, when he was selected to the first of five Pro Bowls. He was voted first-team all-pro by the Associated Press in 1966, '67 and '68.
After he retired, Mr. Mackey joined Mike Ditka as the first tight ends selected to the Pro Football Hall of Fame. The John Mackey Award was established to honor the nation's top college football tight end, and Syracuse retired his number in 2007.
"John was the perfect role model for Syracuse football student-athletes," said Syracuse coach and former NFL player Doug Marrone. "He was a larger-than-life man and he influenced so many people. Many consider him the greatest tight end in NFL history and he was a pioneer in the development in the NFL Players Association."
Mr. Mackey became closely associated with the plight of many former players who helped build the NFL in the era before million-dollar contracts, safer equipment, and better health care.
In later years, he suffered from frontotemporal dementia, which is believed to be caused by the contact associated with playing football. Four years ago, Mr. Mackey entered an assisted-living facility.
The costs associated with his care, which far outpaced Mr. Mackey's pension, led to the "88 Plan" for retired players. Now, former players are pushing for better pension plans and health benefits from the league.