Hecker is a village in Monroe County, Illinois, United States. The population was 475 at the 2000 census.
Hecker was originally named Freedom. The town was laid out on land of Theodore Hilgard. It was platted and surveyed by Thomas Singleton, county surveyor, December 18, 1840, the first home being built in 1849. In 1895 the citizens of what was then Freedom decided to incorporate, to facilitate improvements to the nascent town's infrastructure. Due to complaints from the Post Office, there being another town calling itself Freedom in Illinois, they were forced to change the name. Col. Friedrich Franz Karl Hecker, whose farm was near Summerfield, Illinois in adjacent St Clair County, was known to and well respected by the town's inhabitants, and they decided to honor him by naming the town after him.
Hecker is located at 38°18′20″N 89°59′39″W / 38.30556°N 89.99417°W / 38.30556; -89.99417 (38.305433, -89.994241).