Burg Roßlau, Medieval castle in Dessau-Roßlau, Germany.

Burg Roßlau is a lowland castle at Am Schlossgarten 18b in Roßlau, Dessau-Roßlau, with a residential tower and ring wall dating from before 1400, built on the site of a Slavic settlement fort. Three water moats surround the round castle, which was expanded up to the 16th century. A nearby hunting lodge built in 1740 was once linked to the castle by a bridge.

The castle was built in the 12th century on the remains of an earlier Slavic settlement. Major transformations occurred in the 1830s under Duke Heinrich of Anhalt-Köthen, which established much of the building's current appearance.

The name Roßlau appears in 1358 as rozlowe dat hus, a Slavic-derived form recorded when the princes of Anhalt bought the castle back from the counts of Lindau. The Förderverein Burg Roßlau holds an Easter market and a large Advent market on the second Advent weekend, and the theaterBurg Roßlau stages its Burgtheatersommer in the upper courtyard in late July or August.

Burg Roßlau and the neighbouring hunting lodge stand at Am Schlossgarten 18b in the Roßlau district; both buildings are currently empty and not open to visitors. The grounds are used only during summer open-air events and for the Easter and Advent markets run by the Förderverein Burg Roßlau e.V. The castle courtyard hosts the Burgtheatersommer Rosslau in late July and August.

Excavations on the castle grounds produced a chess piece and a gold ring, the Roßlauer Treuering, considered one of Germany's oldest wedding rings. The medieval residential tower also held a stone-chamber warm-air heating system, a rarity for its period.