Theener is a village in the region of East Frisia, Lower Saxony, Germany. It is an Ortsteil of the municipality of Hagermarsch, part of the municipal association (Samtgemeinde) of Hage. It is a dispersed settlement to the south of Hilgenriedersiel. Historically, the village was first recorded in 1787 as Thener and has been officially registered under its current name since 1818.