Bjaðǫk was a twelfth-century woman purported to have been the mother of Eysteinn Haraldsson, King of Norway. In the first half of the twelfth century, Eysteinn was brought to Norway and claimed to be the son of his royal predecessor, Haraldr gilli, King of Norway. The latter was himself the son of a Gaelic woman, and claimed to be the son of an earlier king. The claims of Bjaðǫk and Eysteinn were accepted, and the latter went on to rule as king for fifteen years. Bjaðǫk's name could to be an Old Norse form of a Gaelic name, and she may well have been a member of a prominent family. According to modern tradition, Haraldr gilli's wife was an aunt of Somairle mac Gilla Brigte, King of the Isles, although whether this tradition is authentic is uncertain.