NFL great Alex Karras -- who also played Mongo in "Blazing Saddles" -- died this morning after suffering kidney failure ... this according to a family spokesperson.
Karras had been battling a myriad of illnesses over the past 2 years, including kidney disease, heart disease, stomach cancer and dementia.
Karras was a punishing defensive superstar on the Detroit Lions from 1958 to 1970 ... before breaking out in Hollywood.
Besides "Blazing Saddles," Karras also had a starring role on the '80s sitcom "Webster"
He was 77.