Grimsby or Great Grimsby is a port town and the administrative centre of North East Lincolnshire, Lincolnshire, England. Grimsby adjoins the town of Cleethorpes directly to the south-east forming a conurbation. Grimsby is 45 mi (72 km) north-east of Lincoln, 33 mi (53 km) (via the Humber Bridge) south-south-east of Hull, 28 mi (45 km) south-east of Scunthorpe, 50 mi (80 km) east of Doncaster and 80 mi (130 km) south-east of Leeds.

Grimsby has notable landmarks including Grimsby Minster, Port of Grimsby, Cleethorpes Beach and Grimsby Fishing Heritage Museum. Grimsby was once the home port for the world's largest fishing fleet around the mid-20th century, but fishing then fell sharply. The Cod Wars denied UK access to Icelandic fishing grounds and the European Union used its Common Fisheries Policy to parcel out fishing quotas to other European countries in waters within 200 nmi (370 km) of the UK coast. Grimsby suffered post-industrial decline like most other post-industrial towns and cities. Food production has been on the rise in the town since the 1990s. The Grimsby–Cleethorpes conurbation acts as a cultural and economic centre for much of north and east Lincolnshire. Grimsby people are called Grimbarians; the term codhead is also used jokingly, often for football supporters. Great Grimsby Day is 22 January. Grimsby is the second largest settlement by population in Lincolnshire after Lincoln.