Tangermünde (German: [taŋɐˈmʏndə] ^ⓘ; Low German: Tangermünn) is a historic town on the Elbe River in the district of Stendal, in the northeastern part of Saxony-Anhalt, Germany. The town has land area of around 89.87 sq.km (34.70 sq.mi) and a population of 10,283 people as of 2022.

Tangermünde is situated in the historic Altmark region of the North German Plain, on a glacial terminal moraine, above the left shore of the Elbe. The town's name derives from the mouth (German: Mündung) of the Tanger tributary. The altitude protects it from floods.

Since the administrative restructuring effective January 1, 2010, the area of Tangermünde comprises the former municipalities of Bölsdorf, Buch, Grobleben, Hämerten, Langensalzwedel, Miltern, and Storkau. These former municipalities are now Ortschaften (divisions) of the town Tangermünde.

Tangermünde can look back at a thousand-year-long history as already in 1009 the medieval chronicler Bishop Thietmar of Merseburg referred to a local lowland castle, which probably had been erected in the early 10th century during the rule of King Henry the Fowler at the border with the lands of the Polabian Slavs incorporated into the Saxon Marca Geronis.

The town itself was first mentioned in a 1275 deed, governed by a succession of vogts (reeves), such as Ruthger von Blumenthal. Due to its favourable location, it soon became a point where tolls were charged on boats sailing along the Elbe River as well as a residence of the Ascanian margraves of Brandenburg. Margrave John II hid his treasure under the parish church, and passed the secret to his brother Otto with the arrow. When the latter was held to ransom by the citizens of Magdeburg in 1278, he used the treasure to pay for his release.

Upon the extinction of the Ascanian dynasty, the town was one of the favourite places of the Luxembourg emperor Charles IV, who had purchased the Margraviate of Brandenburg in 1373 and had Tangermünde Castle (German: Burg Tangermünde) rebuilt as a Kaiserpfalz, including a chapter of Canons Regular. From 1415 onwards, it became the residence of the Hohenzollern electors, after the Nuremberg burgrave Frederick VI was enfeoffed with Brandenburg by Charles' son Emperor Sigismund.

The 15th century marked the "Golden Age" of Tangermünde, an affluent member of the Hanseatic League, when numerous Brick Gothic buildings including the town hall and St. Stephen's parish church arose, surrounded by an almost entirely preserved city wall with well-fortified gates and the castle complex. However, after a 1488 revolt of the Tangermünde citizens against an excise tax on beer, the town lost the grace of Elector John Cicero, and the residence was relocated to Berlin-Cölln.

On 13 September 1617 Tangermünde was almost completely destroyed by a fire, allegedly started as an act of revenge by a townswoman who had vainly sued at the local court for her inheritance. Accused of arson and burned at the stake in 1619, her story was perpetuated by Theodor Fontane's historical novel Grete Minde. The town was rebuilt with a variety of half-timbered houses lending it a unique appearance. However, after the castle had been slighted by Swedish troops during the Thirty Years' War in 1640, Tangermünde lost its strategic importance. Elector Frederick III (as Frederick I King in Prussia from 1701 on) had a local administrative building erected in 1699. The present-day complex is a reconstruction of the early 20th century.