Tormod Kark (Þormóðr Karkr) was the slave and friend of Håkon Sigurdsson (Hákon earl). Hoping for a reward, Kark killed the wanted earl and brought his head to enemy Olaf Tryggvason, later king of Norway. The murder happened at Rimul in Melhus. However, as a punishment for betraying his lord, Kark was himself decapitated, and his head reputedly sat on a stake in Munkholmen alongside the earl's head. The events are described in the Saga of king Olaf Tryggvason[1] in Snorri Sturluson's Heimskringla.
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Tormod Kark Wikipedia(Text) CC BY-SA