Henry is a city in Marshall County, Illinois, United States. The population was 2,540 at the 2000 census. It is part of the Peoria, Illinois Metropolitan Statistical Area.
Henry is located at 41°6′47″N 89°21′37″W / 41.11306°N 89.36028°W / 41.11306; -89.36028 (41.113152, -89.360218).
According to the United States Census Bureau, the city has a total area of 1.5 square miles (3.8 km²), of which, 1.4 square miles (3.6 km²) of it is land and 0.1 square miles (0.2 km²) of it (4.79%) is water.