Posen may refer to:

• Poznań (German: Posen), city in Poland
• Grand Duchy of Posen, autonomous province of Prussia, 1815–1848
• Province of Posen, Prussian province, 1848–1918
• Posen (region), the south-western part of the Province of Posen
• Posen-West Prussia, German province, 1922–1938
• Reichsgau Posen, occupied in 1939, annexed and directly incorporated into the German Reich

• Posen, Illinois, a village
• Posen, Washington County, Illinois, an unincorporated community
• Posen, Michigan
• Posen Township, Michigan
• Posen Township, Minnesota

• Posen (surname)
• SMS Posen, a German dreadnaught, 1908–1922

• Posner (disambiguation)
• Pozen (disambiguation)
• Poznań (disambiguation)