Oesede, Benedictine monastery in Georgsmarienhütte, Germany.

Kloster Oesede is a former Benedictine nunnery in Georgsmarienhütte, Lower Saxony. Its former monastery church, now the Catholic parish church of St. Johann, is built of rough brown and grey stone blocks. The facade rises to a steep gable with a round-arched entrance and a circular window above it, and a square tower on the left is topped by a slate spire with a greenish copper onion dome.

Kloster Oesede was founded in the second half of the 12th century by Count Ludolf von Oesede and his wife Thedela von Schwalenberg, who gave their castle for the purpose. Their daughter Goda, already a nun at Willebadessen, returned as first prioress, and the first nuns began work on 15 January 1170. From 1481 the house belonged to the Bursfeld Congregation and in 1738 received abbey status. A state commission closed it on 14 February 1803; the last abbess was Henriette Mechtild von Schmittmann, and the nuns had to leave by 1 April 1803.

The monastery was founded in the second half of the 12th century by Count Ludolf von Oesede and his wife Thedela von Schwalenberg, who gave their ancestral castle for the purpose. It was dedicated to the Virgin Mary, the Holy Cross and John the Baptist. Their daughter Goda, already a nun at Willebadessen, returned as first prioress, and her sister Regenwita served as sacristan.

The former monastery church, now the Catholic parish church of St. Johann, stands in the Georgsmarienhütte district of Kloster Oesede and is a listed building. The medieval Hagioskop, a small wall opening also called the leper's slit, was uncovered around 1980 in the north side of the eastern nave; look for it inside. The monastery itself was dissolved in 1803, so the church is the main structure to visit.

The monastery was never restored: a state commission declared it closed on 14 February 1803, the nuns had to leave by 1 April, and the inventory was sold on 12 April. The church silver and liturgical vessels stayed in the church, which became the village church and was raised to parish church in 1904.