LOS ANGELES (AP) - Alex Karras has died. The former defensive tackle of the Detroit Lions, who had a successful movie and TV career after retiring from the NFL, passed away at the age of 77. Karras played all 12 of his NFL seasons with the Lions and was an All-Pro four times. His reputation grew as the result of author George Plimpton's book, Paper Lion, about his attempt to try out for the team. When the book was turned into a movie, Karras played himself. He later appeared in the Mel Brooks comedy,"Blazing Saddles", as Mongo. One of his most memorable scenes was when he punched a horse in the mouth, knocking it down. Karras also had success on television, both in the broadcast booth for Monday Night Football and as an actor. He starred in the sitcom, "Webster." His attorney, Craig Mitnick, says Karras died at his home with his family. He had been suffering from dementia and was a leader in the lawsuit filed against the NFL regarding the league's treatment of head injuries.