The Mormaer of Caithness was a vassal title mostly held by members of the Norwegian nobility based in Orkney from the Viking Age until 1350. The mormaerdom was held as fief of Scotland and the title was frequently held by the Norse Earls of Orkney, who were thus a vassal of both the King of Norway and the King of Scots. There is no other example in the history of either Norway or of Scotland in which a dynasty of earls owed their allegiance to two different kings.