Dagenham () is a town in East London, England, within the London Borough of Barking and Dagenham. Dagenham is centred 11.5 miles (18.5 km) east of Charing Cross.
It was historically a rural parish in the Becontree Hundred of Essex, stretching from Hainault Forest in the north to the River Thames in the south. Dagenham remained mostly undeveloped until 1921, when the London County Council began construction of the large Becontree housing estate. The population significantly increased as people moved to the new housing in the early 20th century, with the parish of Dagenham becoming Dagenham Urban District in 1926 and the Municipal Borough of Dagenham in 1938. In 1965 Dagenham became part of Greater London when most of the historic parish become part of the London Borough of Barking.
Dagenham was chosen as a location for industrial activity and is perhaps most famous for being the location of the Ford Dagenham motor car plant where the Ford sewing machinists strike of 1968 took place.