Former NFL star Alex Karras has died due to complication related to a recent kidney ailment. The former Detroit Lions defensive tackle was 77-year-old.

"After a heroic fight with kidney disease, heart disease, dementia and for the last two years, stomach cancer," Karras died at his home, surrounded by family, the spokesman said.

Karras, known to many football fans as “The Mad Duck,” played defensive tackle for the Lions from 1958 to 1970 and was part of the team's infamous "Fearsome Foursome" defensive unit of the early 1960s. After football, he turned to acting and starred most notably in the ABC sitcom “Webster” (1983-87), alongside his real-life wife Susan Clark, as the titular character's adoptive father.

In recent years, Karras played an intricate role in the concussion lawsuit against the NFL involving more than 3,000 former players. He has had several health setbacks including cancer and dementia, presumably as a result of his time in the NFL.

His wife, "Webster” co-star Susan Clark, said in April that Karras suffered from dementia. According to the Washington Post, she later added that his current condition saw him unable to even get behind the wheel of a car.

“This physical beating that he took as a football player has impacted his life, and therefore it has impacted his family life,” Clark said 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.”

Karras leaves behind a wife, and five children.