In the 1980s, he played a sheriff in the comedy "Porky's" and became a hit on TV as Emmanuel Lewis' adoptive father, George Papadapolis, in the sitcom "Webster."
"I had a very heavy heart this morning and I did not know why. I understand now," Lewis said. "Rest in peace, my friend."
Karras also had roles in "Against All Odds" and "Victor/Victoria." He portrayed the husband of famed female athlete "Babe" Didrikson Zaharias in the TV movie that starred Clark in the title role. The two later formed their own production company.
Clark has said that Karras started to show signs of dementia more than a dozen years ago, and she said his quality of life had deteriorated because of head injuries sustained during his playing career. He could no longer drive and couldn't remember recipes for some of the favorite Italian and Greek dishes he used to cook, she said.
In April, he became the lead plaintiff in a suit filed in U.S. District Court in Philadelphia. He is among about 3,500 retired football players who accuse the league of not protecting them better from head injuries.
"This physical beating that he took as a football player has impacted his life, and therefore it has impacted his family life," Clark told the AP earlier this year. "He is interested in making the game of football safer and hoping that other families of retired players will have a healthier and happier retirement."
The NFL maintains that it did not intentionally seek to mislead players and says it has taken action to better protect players and advance the science of concussion management and treatment.
"It's an ironic tragedy that Alex had to live with devastating effects from playing the game he loved," Mitnick said.
He said the NFL on Aug. 30 filed a motion to dismiss all the players' actions, and the plaintiffs' response is due Oct. 30.
Mitnick said the family hasn't decided whether to donate Karras' brain for study, as other families have done. The family released a statement listing his other ailments as kidney failure, which recently hospitalized him, stomach cancer and heart disease.
Karras later wrote an autobiography, "Even Big Guys Cry," and two other books, "Alex Karras' and "Tuesday Night Football."
In addition to Clark, his wife of 37 years, he is survived by their daughter and his four children from his first marriage to the late Joan Powell.
AP Sports Columnist Tim Dahlberg, AP Pro Football Writer Howard Fendrich and AP Television Writer Frazier Moore contributed to this report.
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