MS Oldenburg[a] was the fourth vessel of the Helgoland class of battleships of the Imperial German Navy. Oldenburg's keel was laid in October 1908 at the Schichau-Werke dockyard in Danzig. She was launched on 30 September 1909 and was commissioned into the fleet on 1 May 1912. The ship was equipped with twelve 30.5 cm (12 in) guns in six twin turrets, and had a top speed of 21.2 knots (39.3 km/h; 24.4 mph). Oldenburg was assigned to I Battle Squadron of the High Seas Fleet for the majority of her career, including World War I.
Along with her three sister ships, Helgoland, Ostfriesland, and Thüringen, Oldenburg participated in all of the major fleet operations of World War I in the North Sea against the British Grand Fleet, including the Battle of Jutland on 31 May and 1 June 1916, the largest naval battle of the war. The ship also saw action in the Baltic Sea against the Imperial Russian Navy. She was present during the unsuccessful first incursion into the Gulf of Riga in August 1915, though she saw no combat during the operation.
After the German collapse in November 1918, most of the High Seas Fleet was interned and then scuttled in Scapa Flow during the peace negotiations. The four Helgoland-class ships were allowed to remain in Germany but eventually ceded to the victorious Allied powers as war reparations; Oldenburg was given to Japan, which sold the vessel to a British ship-breaking firm in 1920. She was broken up for scrap in Dordrecht in 1921.