The River Avon ( /ˈeɪvən/) is an English river in the south west of the country. To distinguish it from a number of other Rivers Avon in Britain, this river is often also known as the Lower Avon or Bristol Avon. The name "Avon" is a cognate of the Welsh word afon, "river".

The Avon rises just north of the village of Acton Turville in South Gloucestershire, dividing into two before merging again and flowing through Wiltshire. In its lower reaches from Bath to the Severn Estuary at Avonmouth near Bristol the river is navigable and known as the Avon Navigation.

The Avon is the 19th longest river in the UK at 75 miles (121 km) although there are just 19 miles (31 km) as the crow flies between the source and its mouth in the Severn Estuary.

The name "Avon" is a cognate of the Welsh word afon [ˈavɔn] "river", both being derived from the British language abona, "river". "River Avon", therefore, literally means "River River"; several other English and Scottish rivers share the name.

The County of Avon that existed from 1974 to 1996 covering the Avon valley, including Bristol and Bath, was named after the river.

Bristol ⁱ/ˈbrɪstəl/ is a city, unitary authority area and ceremonial county in South West England, with an estimated population of 433,100 for the unitary authority in 2009, and a surrounding Larger Urban Zone (LUZ) with an estimated 1,070,000 residents in 2007. It is England's sixth and the United Kingdom's eighth most populous city, one of the group of English Core Cities and the most populous city in South West England.

Historically within Gloucestershire, the city received a Royal Charter in 1155 and was granted County status in 1373. From the 13th century, for half a millennium, it ranked amongst the top three English cities after London, alongside York and Norwich, on the basis of tax receipts, until the rapid rise of Liverpool, Birmingham and Manchester during the Industrial Revolution in the latter part of the 18th century. It borders the counties of Somerset and Gloucestershire, and is also located near the historic cities of Bath to the south east and Gloucester to the north. The city is built around the River Avon, and it also has a short coastline on the Severn Estuary, which flows into the Bristol Channel.