Thorfinn 'Skullsplitter' Hausakljufr (Old Norse: Þorfinnr hausakljúfr, "skull-splitter") (died 976) was earl of Orkney. He was the youngest son of Torf-Einarr. Thorfinn married Grelod, daughter of the Mormaer of Caithness and granddaughter of Thorstein the Red. Thorfinn and Grelod had five sons and two daughters. Their son Arnfinn Thorfinnsson married Ragnhild Eiriksdotter, daughter of Eirik Bloodaxe and his widow, Gunnhildr. Thorfinn may have been buried in the broch at Hoxa, on South Ronaldsay.[1] The modern Orcadian beer SkullSplitter is named after him.
The five sons of Thorfinn were Arnfinn, Havard, Hlodvir, Ljot, and Skuli. Arnfinns' wife, Ragnhild Eiriks-Dottir had her husband killed at Murkle in Caithness and married Havard who ruled as earl for a time. Skuli gave allegiance to the Scots king who made him Earl of Caithness and Orkney but never gained control of Orkney, being killed in battle against Ljot in Caithness. Ljot later died in battle, possibly against MacBeth of Moray[2].