220px|right|thumb|First page of the mid-15th century [[Lübeck manuscript of the Chronica slavorum]]
Helmold of Bosau (c. 1120 – after 1177) was a Saxon historian of the 12th century and a priest at Bosau near Plön. He was a friend of the two bishops of Oldenburg in Holstein, Vicelinus (died 1154) and Gerold (died 1163), who did much to Christianize the Polabian Slavs.
History
220px|right|thumb|[[Chronica Slavorum translated into Polish by Jan Papłoński in 1862.]]
Helmold was born near Goslar. He grew up in Holstein, and received his instruction in Brunswick from Gerold, the future bishop of Oldenburg (1139–42). Later he came under the direction of Vicelinus, the Apostle of the Wends, first in the Augustinian monastery of Faldera, afterwards known as Neumünster (1147–53). He became a deacon about 1150, and finally became a parish priest in 1156 at Bosau on Großer Plöner See.
At Bishop Gerold's instigation Helmold wrote his Chronica Slavorum, a history of the conquest and conversion of the Polabian Slavs from the time of Charlemagne