Buddy Ryan (James David Ryan, born February 17, 1934) is a former American football coach.

He was raised in the tiny cotton community of Frederick, Oklahoma. He on many occasions was noted as having superfast reflexes. This allowed him to excel in the ability to pick cotton faster than anyone in Tillman County. After serving in the United States Army during the Korean War as a Master Sergeant, Ryan became an assistant football coach, first at several colleges, then with several professional football teams, starting with the New York Jets in the 1960s. He became a household name of sorts in the early 1980s, while he was the defensive coordinator for the Chicago Bears, working directly under head coach Mike Ditka. After the Bears won the Super Bowl that followed the 1985 regular season in which their defense set several NFL records, Ryan was hired by the Philadelphia Eagles as their head coach.

Ryan immediately became a highly controversial and divisive figure in Philadelphia, releasing running back Earnest Jackson , who had rushed for more than 1,000 yards in both of the previous two seasons (including with the Eagles in 1985) during training camp in 1986. On October 25, 1987 he came under fire again after calling a time-out on the last play of a game against the Dallas Cowboys to score another touchdown when the game's outcome was no longer in doubt. Starting in 1988, Ryan's Eagles did make the playoffs for three straight years, but would lose their first postseason game each time. On November 22, 1989 Ryan found himself at the center of yet another scandal, when Cowboys head coach Jimmy Johnson alleged that Ryan had taken out a "bounty" on two Cowboys players — then-current Dallas (and former Philadelphia) placekicker Luis Zendejas and quarterback Troy Aikman — in a game played on Thanksgiving Day at Texas Stadium. The teams met again on December 10 at Philadelphia in a game marred by the many snowballs thrown by fans.

Ryan was fired by the Eagles on January 7, 1991 after going 43-38-1 in five seasons, and became a commentator before returning to coaching, this time as the head coach of the Arizona Cardinals in 1994. He lasted only two seasons there — where he had a record of 12-20 — before being fired again. He also served as the defensive coordinator for the Houston Oilers.

Despite Ryan's controversial nature his football and coaching accomplishments are many. He served with the staffs of three separate teams to make the Super Bowl on one or more occasions- the Bears, the Vikings, and the Jets. He made his reputation as a defensive specialist, enjoying success wherever he went and implementing and popularising the famous "46" defense in particular. Indeed, the "46" became so effective and well-regarded that it was eventually imitated by every team in the league and its principles are now a standard part of football. Ryan also almost completely rebuilt the Eagles roster into a perennial NFC powerhouse team. He proved himself an excellent judge of talent, stocking the Eagles with players who would lead it to considerable success years after his departure. The 1991 Philadelphia defense, made up of his defensive stars, was arguably one of the greatest defenses of all time, leading the league in passing yards allowed, rushing yards allowed, and several other statistical categories.

Ryan's twin sons also became involved in football coaching and served at the college and professional level.