Thorfinn Torf-Einarsson also known as Thorfinn Skull-splitter was a 10th-century Earl of Orkney. He appears in the Orkneyinga saga and briefly in St Olaf's Saga, as incorporated into the Heimskringla. These stories were first written down in Iceland in the early 13th century and much of the information they contain is "hard to corroborate".

Sigurd Hlodvirsson, popularly known as Sigurd the Stout from the Old Norse Sigurðr digri, was an Earl of Orkney. The main sources for his life are the Norse Sagas, which were first written down some two centuries or more after his death. These engaging stories must therefore be treated with caution rather than as reliable historical documents.