Grimsby, also known as Great Grimsby, is a port town in Lincolnshire, England, situated on the south bank of the Humber estuary near its mouth to the North Sea. It serves as the administrative centre for the unitary authority of North East Lincolnshire, which forms part of the Yorkshire and the Humber region. The town adjoins Cleethorpes to the south-east, creating a significant conurbation that acts as a cultural and economic hub for north and east Lincolnshire.

Settled by Danes in the 9th century, Grimsby derives its name from the Old Norse word for village. It gained a town charter from King John in 1201, establishing its early civic identity. The town experienced significant growth during the industrial era, particularly after the dredging of The Haven and the arrival of the railway in 1848, which facilitated the expansion of its commercial fishing industry and maritime trade networks.

The town is defined by its historic dockland area, featuring landmarks such as the Dock Tower, completed in 1851, and several historic docks including the Royal Dock and Alexandra Dock. Grimsby Minster, formerly St James' Church, stands as a key medieval landmark. The area also includes the Grimsby Fishing Heritage Centre and the Port of Grimsby, reflecting its deep maritime roots and industrial heritage.

Grimsby celebrates Great Grimsby Day on 11 March, commemorating the granting of its town charter in 1201. Residents are known as Grimbarians, a term derived from the town's name. The area offers access to local food production, which has risen since the 1990s, and historical sites related to its past as the world's largest fishing port. The conurbation provides a mix of seaside leisure and industrial tourism.

The population was recorded at 88,243 in the 2011 census, with estimates reaching 88,323 by 2019. The local economy has shifted from fishing to food production and maritime logistics, including oil and car imports via nearby ports. Humberside Airport is located 12 miles west, while road access is provided via the A46 and M180 motorways, connecting the town to Lincoln, Hull, and Doncaster.