Knox had been diagnosed with dementia.
The Seahawks released a statement on Knox's death:
Knox finished his career with a 186-147-1 record. He led his teams to the playoffs 11 times, going 7-11. He made the postseason in each of his first five years in Los Angeles and coached Seattle to four playoff berths in the 1980s, including a trip to the AFC Championship Game in 1983. That campaign marked his Seahawks debut and the first postseason appearance for the franchise, which started playing in 1976.
As Condotta wrote: "He won three NFL Coach of the Year Awards—including in 1984 with Seattle—and earned a reputation for sayings that his players fondly termed 'Knoxisms.' They were as straightforward as the style of play he preferred, such as, 'Play the hand you're dealt' and, 'Football players make football plays.'"
His teams in Seattle were memorable for some of the stars they employed as well, from running back Curt Warner to Hall of Famers in wideout Steve Largent and safety Kenny Easley.
Only Mike Holmgren (86-74) has more wins in Seahawks history than Knox (80-63). Current coach Pete Carroll is 79-48-1.