Karras had been given just days to live after recently experiencing kidney failure. In recent years, Karras had been bravely battling kidney disease, heart disease, stomach cancer and dementia.

The Lions have released the following statement regarding Karras' passing.

"On behalf of the William Clay Ford family and the entire Detroit Lions organization, we extend our deepest sympathies to Susan, the Karras Family and to all of Alex's friends and fans across the country," Lions president Tom Lewand said. "While his legacy reached far beyond the gridiron, we always will fondly remember Alex as one of our own and also as one of the best to ever wear the Honolulu Blue and Silver."

"He was one of the guys that when I was growing up  -- one of the football cards that I had and played with," New England Patriots head coach Bill Belichick told Yahoo! Sports on Wednesday morning. "He was a great player in a great era. Really, it was the growth period there when professional football started to catch up to and overtake college football, and he was a big part of it."

Karras' health has declined in recent years, which Clark attributed to her husband's football career. Karras was among the thousands of former players who have filed lawsuits against the National Football League.