He played football with the Detroit Lions in the National Football League from 1958–1962 and 1964–1970. As an actor, Karras is noted for his role as the thuggish Mongo in the 1974 comedy film Blazing Saddles, and for starring in the ABC sitcom Webster (1983–87) alongside his wife Susan Clark, as the title character’s adoptive father.
On October 8, 2012, it was revealed by friend and auto dealership owner Tom McInerney that Karras had suffered from kidney failure; doctors gave him a few days to live. Karras was treated at the Saint John’s Health Center in Santa Monica, California, before being released into hospice care. After returning to his Los Angeles home with family, Karras died in the morning hours of October 10 from complications caused by kidney failure.