Earl of Orkney, historically Jarl of Orkney, is a title of nobility encompassing the archipelagoes of Orkney and Shetland, which comprise the Northern Isles of Scotland. Originally founded by Norse invaders, the status of the rulers of the Northern Isles as Norwegian vassals was formalised in 1195. Although the Old Norse term jarl is etymologically related to earl, and the jarls were succeeded by earls in the late 15th century, a Norwegian jarl is not the same thing. In the Norse context the distinction between jarls and kings did not become significant until the late 11th century and the early jarls would therefore have had considerable independence of action until that time. The position of Jarl of Orkney was eventually the most senior rank in medieval Norway except for the king himself.
The jarls were periodically subject to the kings of Alba for those parts of their territory in what is now mainland Scotland (i.e. Caithness and Sutherland). In 1232, a Scottish dynasty descended from the mormaers of Angus replaced the previous family descended from the late 10th century jarl Torf-Einarr, although the isles remained formally subject to Norway. This family was in turn replaced by the descendants of the mormaers of Strathearn and later still by the Sinclair family, during whose time Orkney and Shetland became part of Scotland.