Oldenburg

• Mount Oldenburg, Ellsworth Land, Antarctica
• Oldenburg (city), an independent city in Lower Saxony, Germany
• Oldenburg (district), a district historically in Oldenburg Free State and now in Lower Saxony
• Oldenburg in Holstein, a town in Schleswig-Holstein, Germany
• Oldenburg-Land, an association of municipalities near Oldenburg in Holstein
• Oldenburg, Indiana, a town in the United States
• Oldenburg, Texas, a settlement in the United States

• Bishopric of Oldenburg (970–1160), a bishopric that became the Prince-bishopric of Lübeck, now in Schleswig--Holstein
• County of Oldenburg (1091–1774), a state of the Holy Roman Empire, now in Lower Saxony
• Duchy of Oldenburg (1774–1810), a state of the Holy Roman Empire
• Grand Duchy of Oldenburg (1814–1918), a state of the German Confederation and Empire
• Free State of Oldenburg (1918–1946), a state of the Weimar Republic and Nazi Germany
• Oldenburg Land, a historical region in Lower Saxony, covering the former free state

• {{ship|German corvette|Oldenburg|F263}}, a German corvette commissioned in 2013
• {{MS|Oldenburg}}, a British passenger ferry
• {{SMS|Möwe|1914}} or Oldenburg, a German cargo ship and auxiliary cruiser
• {{SMS|Oldenburg}}, a World War I battleship
• {{SMS|Oldenburg|1884}}, a German armored coastal defense ship
• {{SS|Oldenburg|1936}}, a German cargo ship and auxiliary cruiser
• Suomen Joutsen or Oldenburg, a full-rigged ship

• Claes Oldenburg (1929–2022), Swedish-born American sculptor
• Oldenburg (surname)

• the Oldenburg or Oldenburger, a horse breed from Lower Saxony
• House of Oldenburg, North German noble family, kings of Denmark
• University of Oldenburg, Oldenburg, Germany

• Duchess of Oldenburg (apple), a Russian apple cultivar also known as Oldenburg
• Geheimrat Dr. Oldenburg, a German apple cultivar also known as Oldenburg
• Oldenberg, a surname
• Oldenburg Baby, an aborted child who survived

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