Some of the notable earls of Orkney mentioned in various historical sources include:
Sigurd the Stout - Known as Sigurd Eysteinsson, he was a powerful Norse earl mentioned in the Orkneyinga saga. Wikipedia
Earl Thorfinn - Also known as Thorfinn Sigurdsson, he was a significant figure in the history of the Norse Earls of Orkney. Wikipedia
St Magnus - The son of Thorfinn, St Magnus is remembered as a martyr and is the patron saint of Orkney. Wikipedia
Sweyn Asleifsson and Earl Rögnavald - These earls played important roles in the later history of the Norse Earldom of Orkney. Wikipedia
Henry Sinclair - Appointed as earl in 1379, his period is seen as the beginning of the end of Norwegian rule over Orkney. ResearchGate
Joan de Moray - Heiress of Bothwell and wife of Archibald the Grim, 3rd Earl of Douglas, she was a direct descendant of Maurice de Moravia, Earl of Orkney. Google Groups
These earls significantly influenced the history and culture of the Orkney Islands during their respective times.