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.^[2] In the Norse context the distinction between jarls and kings did not become significant until the late 11th century^[3] 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.

The second earldom was created by James VI of Scotland in 1581 for his half-uncle Robert Stewart but after only two incumbents the title was forfeited in 1614. After the third creation of 1696, which title still exists today, the earls' influence on Orcadian affairs became negligible.

Rognvald Eysteinsson, Jarl of Møre fl. 865–890 ^{[lower-alpha 1][5][6][7]} is sometimes credited with being the founder of the jarldom. By implication the Orkneyinga saga identifies him as such for he is given "dominion" over Orkney and Shetland by King Harald Finehair, although there is no concrete suggestion he ever held the title. The Heimskringla states that his brother Sigurd was the first to formally hold the title.^[8][9]

Sigurd's son Guthorm ruled for a year and died childless.^[10] Rognvald's son Hallad then inherited the title. However, unable to constrain Danish raids on Orkney, he gave up the jarldom and returned to Norway, which "everyone thought was a huge joke".^[11] Torf-Einarr then succeeded in defeating the Danes and founded a dynasty which retained control of the islands for centuries after his death.^[12] Smyth (1984) concludes that the role of the brothers Eysteinsson lacks historical credibility and that Torf-Einarr “may be regarded as the first historical earl of Orkney”.^[13]

Drawing on Adam of Bremen's assertion that Orkney was not conquered until the time of Harald Hardrada, who ruled Norway from 1043 to 1066, Woolf (2007) speculates that Sigurd “the Stout” Hlodvirsson, Torf-Einarr's great-grandson, may have been the first Jarl of Orkney.^[14] Dates are largely conjectural, at least until his death recorded in 1014.

Assuming Torf-Einarr is a genuine historical figure, all of the subsequent jarls were descended from him, save for Sigurd Magnusson, whose short rule was imposed by his father Magnus Barelegs, and who later became Sigurd I of Norway.^{[lower-alpha 2]}

One of the main sources for the lives and times of these jarls is the Orkneyinga saga, which has been described as having "no parallel in the social and literary record of Scotland".^[17] One of the key events of the saga is the "martyrdom" of Jarl Magnus Erlendsson, later Saint Magnus, c. 1115. The last quarter of the saga is taken up with a lengthy tale of Jarl Rögnvald Kali Kolsson and Sweyn Asleifsson — indeed the oldest version ends with the latter's death in 1171.^[18][19]

After the murder of Jarl Jon Haraldsson some sixty years later, Magnus, son of Gille Brigte became the first of the Scottish earls. He may have been a descendant of Jarl Rögnvald Kali Kolsson, although this has never been corroborated. However, the line of specifically Norse jarls is said to have come to an end when Jarl Magnus II was granted his title by Haakon IV of Norway c. 1236.^[7][20]

After the close of the Jarls' Saga on the death of Jon Haraldsson in 1230, the history of Orkney is "plunged into a darkness which is illuminated by very few written sources".^[41] The first jarl known to have held the title after the Norse dynasty came to and end in 1230 was Magnus II but the title may have been held by an unknown other prior to his investiture.^[42] Although successive jarls of Orkney were related, they each acquired the position by being personally appointed to the role by the Norwegian king; the jarldom was not inheritable.

• Mormaer of Caithness
• Viscount St John