Burnham-on-Sea is a seaside town in Somerset, England, at the mouth of the River Parrett, upon Bridgwater Bay. Burnham was a small fishing village until the late 18th century when it began to grow because of its popularity as a seaside resort.

Burnham-on-Sea forms part of the parish of Burnham-on-Sea and Highbridge and shares a town council with its neighbouring small market town of Highbridge. According to the 2011 census the population of the parish (including Highbridge) was 19,576, of which the most populous wards 'Burnham Central' and 'Burnham North'; totalled 13,601.

Burnham-on-Sea is famous for its low lighthouse. The lighthouse was built in 1832 and is a Grade-II listed building with a red and white striped facade.

The position of the town on the edge of the Somerset Levels and moors where they meet the Bristol Channel, has resulted in a history dominated by land reclamation and sea defences since Roman times. Burnham was seriously affected by the Bristol Channel floods of 1607, with the present curved concrete wall being completed in 1988. There have been many shipwrecks on the Gore Sands, which lie just offshore and can be exposed at low tides. Lighthouses are hence prominent landmarks in the town, with the original lighthouse known as the Round Tower built to replace the light on the top of the 14th-century tower of St Andrews Church. The 110-foot (34-metre) pillar or High Lighthouse and the low wooden pile lighthouse or Lighthouse on legs on the beach were built to replace it. The town's first lifeboat was provided in 1836 by the Corporation of Bridgwater.

The name Burnham is derived from Burnhamm, as it was called in the will of King Alfred, made up from the Old English words Burna meaning stream and Hamm for enclosure. On-Sea was added later as there are several other towns of the same name in England.

The history of Burnham-on-Sea is the history of the reclamation of the Somerset Levels from the River Severn and the Bristol Channel. The Romans were the first peoples to try to reclaim the Somerset levels, and it was their people who were probably the first settlers in the high sand dunes behind the River Parrett. This could have been in part to maintain navigational systems, to aid ships entering the River Parrett and what is now Highbridge. When the Romans left, the system of drainage they installed was not maintained, and the areas reverted to become a tidal salt flat during the Anglo Saxon period.

It is likely that at the time of the Norman Domesday book, settlements existed at Burnham and Huntspill, their common boundary running along what is now the Westhill Rhyne. The church at Burnham and its lands were given to Gloucester Abbey in the 12th century, later transferred to Wells Cathedral along with up to 50 houses surrounding the church. Burnham was part of the hundred of Bempstone.

One of the earliest recorded incidents to affect the town was the Bristol Channel floods of 1607, since when various flood defences have been installed. In 1911 a concrete wall was built. After the Second World War, further additions to the defences against the sea were added by bringing part of the remains of a Mulberry harbour used for the Normandy Landings, and burying them in the sand. Today the town is defended from flooding by a large curved concrete wall, completed in 1988 following serious flooding in 1981. The wall runs along the Esplanade, and serves as the canvas for a wide variety of graffiti and street art.^{[citation needed]}