The Sønder Kirkeby Runestone, listed as runic inscription DR 220 in the Rundata catalog, is a Viking Age memorial runestone that was discovered in Sønder Kirkeby, which is located about 5 kilometers east of Nykøbing Falster, Denmark.
The Sønder Kirkeby Runestone has been known to Danish antiquarians since 1802 when it was discovered in the northwest wall of the church in Sønder Kirkeby. Before the historical significance of runestones was understood, they were often reused as building materials in the construction of roads, bridges, and buildings. The stone was removed by the Danish Antiquarian Commission in 1811, and it is currently on display at the National Museum of Denmark in Copenhagen. The runestone, which is 0.79 meters in height, is known locally as the Sønder Kirkeby-stenen.
The inscription consists of four lines of runic text in the younger futhark that are below the image of a ship. Portions of the inscription and the ship image are damaged, which probably occurred when the stone was sized for use in the church wall. The Sønder Kirkeby Runestone is classified as being carved in runestone style RAK. This is considered to be the classification for the oldest style and is used for inscriptions where the ends of the runic text bands are straight and do not have any attached dragon or serpent heads. The inscription is dated as being carved after the Jelling stones.
The runic text states that the stone was raised by Sassur as a memorial for his brother Ásgautr, with the damaged text reconstructed as stating that the brother died in Gotland, Sweden. Other runestones which mention Gotland include Sö 174 in Aspö, the now-lost U 414 in Norrsunda, U 527 in Frötuna, U 614 in Torsätra, DR 259 in Fuglie, possibly Sö 47 in Vålsta, where the text has been damaged, and with U 375 in Vidbo referring to a location on Gotland.