Thorfinn, known as Thorfinn the Mighty, was the youngest son of Earl Sigurd of Orkney. He inherited his Earldom as a babe in arms when his father was killed at the battle of Clontarf in 1014. Thorfinn’s minority was a time of disruption, but by 1032 he had set about bringing his earldom into order again. Further he extended his “empire” to include not only the Hebrides, Dublin, Sodor and Man, but western and northern regions of Scotland as well.
Thorfinn sized control of Sodor around 1034 when he drove out Harold the Black to exile in Iceland. He appointed a puppet King named Fignall to rule in Harold's place.
His sons Erland and Paul ruled the earldom jointly after his death in 1065, but were unable to prevent considerable loss of territory at the hands of adventurers such as Godred Crovan and others.
- Thorfinn the Mighty (Thorfinn Sigurdsson) is a real historic figure who was Earl of Orkney between 1016 and 1065.