Agathenburg (in High German, in Low Saxon: Gothenborg) is a municipality in the district of Stade, Lower Saxony, Germany.

Lieth, as it was originally named, belonged to the Prince-Archbishopric of Bremen, a territory of imperial immediacy established in 1180.

During the Leaguist occupation under Johan 't Serclaes, Count of Tilly, Lieth suffered from attempts of re-Catholicisation.

In 1648 the prince-archbishopric was transformed into the Duchy of Bremen, which was first ruled in personal union by the Swedish Crown – interrupted by a Danish occupation (1712–1715) – and from 1715 on by the House of Hanover.

The rapid transit system of Hamburg S-Bahn serves Agathenburg with a railway station.