Ryan, a three-time Pro Bowler, was the last quarterback to lead the Cleveland Browns to an NFL championship. His family released a statement announcing his passing, revealing that he had been battling Alzheimer's disease and that chronic traumatic encephalopathy (CTE) was suspected to have played a role in the progression of the disease. In accordance with Ryan's wishes, his brain was donated to Boston University's CTE Center for further study.

The Cleveland Browns expressed their condolences, calling Ryan a Browns icon and championship-winning quarterback. Ryan's football career began at Rice University, where he excelled as a standout quarterback. In the 1958 draft, he was selected by the Los Angeles Rams as the 55th overall pick in the fifth round. After four years with the Rams, Ryan joined the Cleveland Browns, where he had his most successful years.

During his time in Cleveland, Ryan earned three Pro Bowl nods and was a contender for the United Press International NFL MVP in 1965. In 1964, he led the Browns to their fourth NFL Championship, defeating Johnny Unitas and the Baltimore Colts. Ryan's impressive performance included leading the league with 25 touchdown passes and 2,404 passing yards. He continued his success in the following years, throwing 18 touchdowns in 1965 and 29 touchdowns in 1966.

After the 1968 season, Ryan played as a reserve for the Washington Redskins in 1969 and 1970 before retiring from football. However, his journey did not end there. Ryan returned to Rice University to pursue his Ph.D. and later became a math teacher at Case Western Reserve in Cleveland, as well as Yale and Rice. He was also credited with helping create an electronic voting system that modernized the U.S. House of Representatives.

Ryan is survived by his wife Joan, with whom he celebrated their 65th wedding anniversary last year. The news of his passing has left a void in the football community, as both his athletic achievements and intellectual contributions will be remembered. The Associated Press contributed to this report.