Great Grimsby is a constituency in North East Lincolnshire represented in the House of Commons of the Parliament of the United Kingdom since December 2019 by Lia Nici of the Conservative Party. Between 1918 and 1983 it was known simply as Grimsby; following the 2023 Periodic Review of Westminster constituencies, the seat will be subject to boundary changes which will incorporate the neighbouring town of Cleethorpes. As a consequence, it will be renamed Great Grimsby and Cleethorpes, to be first contested at the next general election.

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) 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. In 2021 it had a population of 86,138.