Gellersen is a Samtgemeinde ("collective municipality") in the district of Lüneburg, in Lower Saxony, Germany. Established in 1974, Gellersen was formed from the merger of Reppenstedt, Kirchgellersen, Westergellersen, Südergellersen, Heiligenthal, and Dachtmissen.[1] The seat is in the village Reppenstedt. As of 31 December 2018, it had a population of 14,090.[2]