Caistor is a town and civil parish in the West Lindsey district of Lincolnshire, England. As its name implies, it was originally a Roman castrum or fortress. It lies at the north-west edge of the Lincolnshire Wolds, on the Viking Way, and just off the A46 between Lincoln and Grimsby, at the A46, A1084, A1173 and B1225 junction. It has a population of 2,601. Its name comes from the Anglo-Saxon ceaster and was given in the Domesday Book as Castre.

West Lindsey is a local government district in Lincolnshire, England. Its council is based in Gainsborough, the district's largest town. The district also includes the towns of Caistor and Market Rasen, along with numerous villages and surrounding rural areas. The east of the district includes part of the Lincolnshire Wolds, a designated Area of Outstanding Natural Beauty.