Northolt Mandeville (known as Mandeville until 2002) is an electoral ward in the London Borough of Ealing. It elects three councillors to Ealing London Borough Council.
The ward covers most of the northern half of Northolt, including the historic village centre, which contains the 13th-century St Mary the Virgin church and the 14th-century Northolt Manor archaeological site. It is primarily residential in character, including both interwar housing developments and the postwar Racecourse Estate, but also contains Northolt Industrial Estate as well as several local parks. Islip Manor Meadows nature reserve is located in the southwest of the ward.
It is named for Mandeville Road, which runs from northeast to southwest through the centre of the ward.
The by-election was called following the resignation of Cllr Deirdre Costigan, who had been elected MP for Ealing Southall at the 2024 general election. It was held on the same day as by-elections in Hanger Hill and South Acton wards.
The election took place on the same day as the 2010 general election.
The by-election was called following the death of Cllr Peter Downham.
The by-election was called following the resignation of Cllr Brian Reeves.