The football star-turned-actor passed away on Wednesday (10Oct12), just days after he was discharged from Santa Monica hospital in California to continue with hospice care at home.
He had suffered numerous ailments in recent years and finally succumbed to kidney failure.
A statement from Karras' family spokesperson confirmed the sad news and revealed the star passed away after "a heroic fight with kidney disease, heart disease, dementia and for the last two years, stomach cancer".
Karras began his career in sport, becoming a professional wrestler before playing football for the Detroit Lions after he was drafted into the team in 1958.
He began flirting with acting in the 1960s and turned to the profession full-time after his tenure with the Detroit Lions came to an end in 1971. He was considered for a part in iconic 1972 movie The Godfather, but after missing out, he landed a memorable role as slow-witted Mongo in 1972 comedy Blazing Saddles.
Karras' TV roles included parts in M*A*S*H and The Odd Couple, as well as in 1980s sitcom Webster, in which he starred alongside his real life wife, Susan Clark, and he also worked in sports commentary and coaching.
He hit headlines earlier this year (12) when he filed a lawsuit against America's National Football League (NFL) bosses, alleging they failed to protect him from the concussions he suffered as a Detroit Lions player.
Karras was among hundreds of other former NFL stars who joined a class lawsuit seeking medical monitoring, cognitive health benefits and financial compensation.