The answer.....Sean Payton, the Super Bowl-winning coach of the New Orleans Saints coached for the Giants, but never wore the uniform. Payton served as Jim Fassel's QB coach in 1999 before moving on to OC from 2000-02. Payton did play in the NFL, for what it's worth: he was replacement player for the Bears during the 1987 players' strike.
Tony Dungy (right), who coached the Colts to a Super Bowl several years ago, played for the Pittsburgh Steelers from 1977-78 and the 49ers in 1979. He was a member of the Giants' practice squad in 1980. He never played in a regular season game, however, but he did suit up as a player. A cheap shot, we know....
Before Tom Landry began his career as the iconic coach the Dallas Cowboys in 1960, he spent ten seasons as a player and coach for the Giants. Landry was a solid defensive back, but he was an innovator as a coach. In 1954, head coach Jim Lee Howell allowed Landry to both play and coach. He retired after the 1955 season as a player and dedicated the next four seasons to making the Giants' defense one of the best in the NFL.
Don McCafferty is a figure not many know much about. He was a Paul Brown disciple, having played for the great coach at Ohio State, but World War II disrupted McCafferty's transition from college to the pros. He played one season for the Giants (1946) as a wide receiver before turning to the coaching ranks at Kent State University, where he stayed for 11 years. From there McCafferty moved back to pro ball, joining Weeb Ewbank's staff in Baltimore. He then coached under Don Shula after Ewbank left for the Jets, and took over as head coach when Shula moved on to coach the Dolphins in 1970.
The Colts won Super Bowl V under McCafferty, 16-13, over Landry's Cowboys.