Wintershall Dea AG was a German energy company with a long history in the exploration and production of natural gas and crude oil. The company was formed in 2019 through the merger of Wintershall Holding GmbH and DEA Deutsche Erdoel AG, combining two German companies with roots going back more than a century. It operated internationally across oil and gas exploration, production, development and related midstream activities, with headquarters historically located in Kassel and Hamburg, Germany. Wintershall Dea became a joint-stock company (AG) in July 2021. However, its business has changed substantially: on 3 September 2024, most of its E&P and carbon-storage assets outside Russia were transferred to Harbour Energy, and the remaining company is focused on managing/divesting its remaining assets and ultimately winding down operations.