Dagenham () is a town in East London, England, within the London Borough of Barking and Dagenham. It is centred 11.5 miles (18.5 km) east of Charing Cross, with Barking to the west, Romford and Hornchurch to the north-east, and Rainham to the south-east. Dagenham Dock, on the River Thames, is to the south.
Originally a rural area in Essex, Dagenham remained mostly undeveloped until 1921, when the London County Council began construction of the large Becontree estate. Dagenham Urban District was created in 1926, and became a municipal borough in 1938. When Greater London was created in 1965, most of the area covered by the municipal borough became part of the London Borough of Barking, which was renamed Barking and Dagenham in 1980.