Green's family made the announcement in a statement to NFL Media Insider Ian Rapoport. "His family was by his side and he fought hard," the statement read.
Cunningham, who credits Green for revitalizing his NFL career, said he "built our morals, our character, our integrity," by being a great players' coach.
"He was a man who really, really cared," Cunningham said Friday on NFL Network. "I believe that without God using Dennis Green, I probably would not have played football as long as I played."
A native of Harrisburg, Pennsylvania, Green spent 17 years as an NFL coach, compiling a 113-94 regular-season mark, with a 4-8 record in the postseason. His 113 wins place Green 33rd on the NFL's all-time list. Before taking over the Vikings, Green served as head coach at Northwestern from 1981 to 1985 before coaching at Stanford from 1989 to 1991.
The passionate, emotional Green is fondly remembered for his 2006 postgame meltdown as coach of the Cardinals, ranting to a packed conference room after an ugly loss to the Bears: "They are who we thought they were, and we let 'em off the hook!"
That clip -- still played regularly during the football season -- was a snapshot of Green's gritty, live-wire personality. His motto as a coach -- "Plan your work and work your plan" -- was something he carried beyond his NFL days to later coaching stints with the UFL's California Redwoods and Sacramento Mountain Lions.
"Denny Green, for all the years that I've been in this business, is the best coach I've ever been around or known with regards to an eye for talent," former NFL coach and NFL Network analyst Brian Billick said on NFL Network. "Whether it was the draft, whether it was free agency, whether it was getting the most out of the players that you had."
"He was my wide receiver coach for so many years and we stayed friends over the years also. So I'm real saddened by it," Hall of Fame receiver Jerry Rice said from the American Century Championship. "He really did a lot for my career, because he was one of those coaches that never let me get complacent and he never let me felt like I had arrived. ... He was the type of coach that really influenced me throughout my career. ... He was more than a coach. He as almost like, you know, my best friend. Someone I could always depend on, someone -- even I was having some difficult times -- he had something positive to say to get me going."
"He mentored countless players and served as a father figure for the men he coached," the statement read. "He took great pride in helping assistant coaches advance their careers. His tenure as one of the first African American head coaches in both college and the NFL was also transformative. Our thoughts and prayers are with the entire Green family."
"All of us at the Cardinals are incredibly saddened by the news of Dennis Green's passing. Coach Green will rightly be remembered as a true innovator, leader and pioneer among football coaches. We express our deepest sympathy to his family and his many friends."
In a statement released by the league, Troy Vincent, NFL executive vice president of football operations, described Green as a terrific head coach" who "helped pave the way for minority coaches"
Named as the fifth coach in Vikings history in 1992, Green became just the second African American head coach in the NFL's modern era following Art Shell. In Minnesota, Green made an immediate impression with scribes and fans by announcing there was a "new sheriff in town."
More than a sheriff, Green goes down as one of the most memorable NFL figures of the 1990s, a coach beloved by his players and assistants -- and an unforgettable personality.