Grimsby, also Great Grimsby, is a large coastal English seaport and administrative centre in North East Lincolnshire, on the South Bank of the Humber Estuary, close to where it reaches the North Sea. It ran the largest fishing fleet in the world by the mid-20th century, but fishing declined dramatically after the Cod Wars denied UK access to Icelandic fishing grounds, and the European Union parcelled out fishing quotas in waters within a 200-mile limit of the UK coast to other European countries, in line with its Common Fisheries Policy.

Since then Grimsby has suffered post-industrial decline, although food manufacturing has been encouraged since the 1990s. The Grimsby–Cleethorpes conurbation acts as a cultural, shopping and industrial centre for much of northern and eastern Lincolnshire. Grimsby people are called Grimbarians; the term codhead is also used jokingly, often for Grimsby football supporters.