Chatteris /ˈtʃætɛrɪs/ is a market town and civil parish in the Fenland district of Cambridgeshire, England, situated in The Fens between Huntingdon, March and Ely. The town is in the North East Cambridgeshire parliamentary constituency.
The parish of Chatteris is large, covering 6,099 hectares, and for much of its history was a raised island in the low-lying wetland of the Fens. Mentioned in the Domesday Book of 1086, the town has evidence of settlement from the Neolithic period. After several fires in the 18th and 19th centuries, the majority of the town's housing dates from the late Victorian period onwards, with the tower of the parish church the only medieval building remaining.
Following the draining of the Fens, beginning in the 17th century and completed in the 19th century, the town's economy has been based on agriculture and related industry. Due to its proximity to Cambridge, Huntingdon and Peterborough, the town has emerged as a commuter town. The town had a population of 11,011 at the time of the United Kingdom Census 2021.