James Thomas Clack (October 26, 1947 – April 7, 2006) was an American football guard in the National Football League. He played for 11 seasons between 1971 and 1981. He died of heart failure in 2006 after suffering from cancer for four years.
Clack graduated from Wake Forest University. He began his career with the Pittsburgh Steelers, and he was part of two Super Bowl championship teams in 1974 and 1975.
In April 1978, the Steelers traded Clack (along with wide receiver Ernie Pough) to the New York Giants in exchange for offensive lineman John Hicks. Clack spent four seasons with the Giants.
It was his snap that Joe Pisarcik fumbled away to Herman Edwards at the end of the November 19, 1978 game between the Giants and Edwards' Philadelphia Eagles at Giants Stadium, costing the team a certain victory in a play since known as "The Miracle at the Meadowlands" to Eagles' fans and "The Fumble" to Giants' fans (Clack had snapped it earlier than Pisarcik, still trying to get his team on board a controversial play call, expected due to the imminent expiration of the play clock).
Clack was inducted into the Wake Forest's hall of fame in 1981, and into the North Carolina Sports Hall of Fame in 2004.