Berzerker according to Wikipedia

Berserkers (or berserks) were Norse warriors who are reported in the Old Norse literature to have fought in a nearly uncontrollable, trance-like fury, a characteristic which later gave rise to the English word berserk. Berserkers are attested in numerous Old Norse sources.

The Úlfhéðnar (singular Úlfhéðinn), mentioned in the Vatnsdœla saga, Haraldskvæði and the Völsunga saga, were said to wear the pelt of a wolf when they entered battle. Úlfhéðnar are sometimes described as Odin's special warriors, with the pelt from a wolf and a spear as distinguishing features.