Jon Francis Koncak (born May 17, 1963) is a former American professional basketball player. A 7'0" center from Southern Methodist University, Koncak was selected with the 5th pick in the 1985 NBA Draft by the Atlanta Hawks. Koncak spent ten seasons with the Hawks (1985–1995), mainly in a reserve role, then concluded his career with the Orlando Magic. He retired in 1996 with career totals of 3,520 points and 3,856 rebounds.
Though a reliable defender for much of his career, Koncak is perhaps best remembered for the six-year, US$ 13 million contract he received from the Hawks in 1989 – an unprecedented total for a reserve. As a result, he earned the derisive nickname "Jon Contract".
On February 23, 2008 SMU retired Koncak's jersey. Koncak is an Eagle Scout.