Brentford is a suburban town in West London, England and part of the London Borough of Hounslow. It lies at the confluence of the River Brent and the Thames, 8 miles (13 km) west of Charing Cross.

Its economy has diverse company headquarters buildings which mark the start of the M4 corridor; in transport it also has two railway stations and Boston Manor Underground station on its northwest border with Hanwell. Brentford has a convenience shopping and dining venue grid of streets at its centre. Brentford at the start of the 21st century attracted regeneration of its little-used warehouse premises and docks including the remodelling of the waterfront to provide more economically active shops, townhouses and apartments, some of which comprise Brentford Dock.

A 19th- and 20th-century mixed social and private housing locality, New Brentford is contiguous with the Osterley neighbourhood of Isleworth and Syon Park and the Great West Road which has most of the largest business premises.

The name is recorded as Breguntford in 705 in an Anglo-Saxon charter and means ford over the River Brent'.

The name of the river derives from * brigant-, a Brythonic word, meaning "high" or "elevated" (possibly in a holy sense). The river may also have been associated with the goddess Brigantia. The suffix '-ford' is Old English. The ford was most likely located where the main road crossed the river. New Brentford is recorded as Newe Braynford in 1521 and was previously known as Westbraynford. Old Brentford is recorded as Old Braynford in 1476 and was previously known as Estbraynford.

The settlement pre-dates the Roman occupation of Britain, and thus pre-dates the founding of nearby London. Many pre-Roman artefacts have been excavated in and around the area in Brentford known as 'Old England'. Bronze Age pottery and burnt flints have been found at separate sites in Brentford. The quality and quantity of the artefacts suggests that Brentford was a meeting point for pre-Romanic tribes. One well known Iron Age piece from about 100 BC – AD 50 is the Brentford horn-cap – a ceremonial chariot fitting that formed part of local antiquarian Thomas Layton's collection, now held by the Museum of London. The Celtic knot pattern (the 'Brentford Knot') on this item has been copied for use on modern jewellery.

An amateur local history and an inscription outside the County Court claim that Julius Cæsar crossed the Thames here during his invasion of Britain in 54 BC, and fought a battle with Cassivellaunus close by. Cæsar describes the place as fortified with sharp stakes. The discovery of sharp stakes in the riverside at Brentford Dock in the early 20th century was taken by Montagu Sharpe as evidence of a fortified crossing-site, and Caesar's battle. The stakes were removed as a hazard to river traffic, and Sharpe's claims are not supported by further excavations.

Historically part of Middlesex, in the southeastern corner of Elthorne Hundred, it has formed part of Greater London since 1965.