Godmanchester is a town and civil parish in the Huntingdonshire district of Cambridgeshire, England. It is separated from Huntingdon, 1.2 miles (1.9 km) to the north, by the valley of the River Great Ouse. Being on the Roman road network, the town has a long history. It has a waterside location, surrounded by open countryside of high value for its biodiversity but it remains highly accessible, with a railway line to London, the A1 road and M11/A14 which run nearby.

The root name itself is uncertain but the same as the town of Godalming, suggesting it may be derived from the ethnonym of the Goths who settled Sub-Roman Britain. The second element mund is the nominative plural of the Old English word munda, meaning "protector" or "guardian." The suffix chester derives from the Middle English cognate of the Latin word castrum, and was used by the Anglo-Saxons to denote the location of a former Roman (or sometimes pre-Roman) military fort.

The most likely translation is thus the nouns "Goths-guards-fort." Attributions to the Saxon King Guorum c.835–890 are considered to be ahistorical founding myths reflective of the changes in Anglo-Saxon perceptions of the Goths over time.

A minority of visitors, former residents and residents continue to pronounce the place as Gumster, though this has long-since been superseded by Godmunchester, with stress on the first syllable.