Mazon (/məˈzɒn/) is a village in Mazon Township, Grundy County, Illinois, United States. The population was 1,015 at the 2010 census. The center of population of Illinois is located in Mazon. Illinois' State Fossil, the unique and bizarre Tully Monster was first found in nearby Mazon Creek. Mazon was formerly served by the Santa Fe railway at the Mazon Depot. It was established in 1876.