Southport is a seaside town in the Metropolitan Borough of Sefton in Merseyside, England. It lies on the West Lancashire coastal plain and the east coast of the Irish Sea, approximately 17 miles (27 km) north of Liverpool and 15 miles (24 km) southwest of Preston. At the 2021 census, Southport had a population of 94,421, making it the eleventh most populous settlement in North West England and the third most populous settlement in the Liverpool City Region.

The town was founded in 1792 by William Sutton, an innkeeper from Churchtown, who built a bathing house at what is now the south end of Lord Street. The area was previously known as South Hawes, and was sparsely populated and dominated by dunes. The area became popular with tourists due to the easy access from the nearby Leeds and Liverpool Canal, and by 1848 had a railway connection. The resort increased during the Victorian era and contains examples of Victorian architecture and town planning. Lord Street was developed as a wide, tree-lined shopping street, and attractions such as Southport Pier, which is the second longest seaside pleasure pier in the British Isles, were constructed. A particular feature of the town is the extensive tree planting. This was one of the conditions required by the Hesketh family when they made land available for development in the 19th century. Hesketh Park at the northern end of the town is named after them, having been built on land donated by Rev. Charles Hesketh.

Extensive sand dunes stretch for several miles from Woodvale to Birkdale, the south of the town. The Ainsdale dunes have been designated as a national nature reserve and a Ramsar site. Local fauna include the natterjack toad and the sand lizard. Southport hosts events, including an annual air show on and over the beach, the largest independent flower show in the UK in Victoria Park, and the British Musical Fireworks Championship. The town is at the centre of England's "Golf Coast", and has hosted the Open Championship at the Royal Birkdale Golf Club.

The town gets its name from the South Port Hotel; built around 1797 (see #18th century).

There have been settlements in the area now comprising Southport since the Domesday Book, and some parts of the town have names of Viking origin. The earliest recorded human activity in the region was during the Middle Stone Age when mesolithic hunter-gatherers were attracted by the abundant red deer and elk populations, as well as the availability of fish, shellfish, and woodland.

Roman coins have been found at Halsall Moss and Crossens, although the Romans never settled southwest Lancashire.

The first objective evidence of an early settlement in the region is in the Domesday Book, in which the area is called Otergimele. The Domesday Book states that there were 50 huts in Otergimele, housing a population 200. The population was scattered thinly across the region, and it was at the northeast end of Otergimele (present-day Crossens), where blown sand gave way to alluvial deposits from the River Ribble estuary, that a small concentration of people occurred.

It was here that a primitive church might have been built, which gave the emerging village its name of Churchtown, the parish being North Meols (pronounced "meals"). A church called St Cuthbert's is still at the centre of Churchtown.