Langelsheim is a town in the district of Goslar in Lower Saxony, Germany.

The municipality is situated between the river Innerste and its tributary the river Grane, on the northern edge of the Harz mountain range and the Harz National Park, located about 8 km (5.0 mi) northwest of Goslar.

Langelsheim is divided into eight Ortschaften[3] with the following population as of 30 June 2020:[4] The place once called Langenizze developed in the 10th century out of a hill fort at the Kahnstein mountain, erected by the Ottonian dynasty.

Langelsheim was the site of historic ironworks, first documented in the 13th century, where ore from the Mines of Rammelsberg was smelted.

The former municipalities Hahausen, Lutter am Barenberge and Wallmoden are part of Langelsheim since 1 November 2021.