Thorfinn Skullsplitter was a 10th-century Jarl (earl) of Orkney, the youngest son of Torf-Einarr, himself the son of Rognvald Eysteinsson, the first Jarl of Orkney.
Torf-Einarr had two other sons, Arnkel and Erlend, who “fell in a war expedition” at an unspecified location in England along with Eric Bloodaxe.
Thorfinn had five sons – Arnfinn, Havard, Hlodvir, Ljot, and Skuli. Their mother was Grelad, who was a daughter of Earl Dungad of Caithness and Groa (a daughter of Thorstein the Red).
Thorfinn Torf-Einarsson lived to be an old man and died c. 963 “on a bed of sickness”. He is believed to have been buried at the broch site at Howe of Hoxa, on South Ronaldsay.
According to ‘St Olaf’s Saga’, his sons became Jarls after him but then the earldom faced trouble and dynastic strife. Thorfinn’s daughter-in-law Ragnhild had her husband, Arnfinn, killed at Murkle, in Caithness. She then married his brother Havard “Harvest-happy”, who subsequently ruled as Jarl for a time.
Not content with this new arrangement, Ragnhild then conspired with her nephew, Einar Kliningr, who killed Havard at the battle of Havarðsteiger, near Stenness.
Einar and Ragnhild then fell out and the latter persuaded Einar Harðkjotr to attack and kill his cousin, Einar Kliningr.
However, Ragnhild's ambitions were still not assuaged and she then colluded with Ljot Thorfinnson, whom she married, and he had the second Einar killed. Having now married three of Thorfinn’s sons in succession, no more is told of Ragnhild. Ljot became Jarl and an “excellent leader”.
There is, rather disappointingly, no explanation of how Thorfinn came by the name “Skullsplitter” and there are no surviving accounts, whether historical or legendary, that ascribe any heroic or bloodthirsty deeds to our Thorfinn.
Of course, it is worth mentioning that the Vikings were not without a sense of humour in the nicknames they bestowed on people. There was, for example, a Thorfinn the Short who was actually noted for being very tall, and it is therefore within the bounds of possibility that Thorfinn “Skullsplitter” was so named because he was a gentle old soul who wouldn’t have hurt the proverbial fly.