Berserkir (singular Berserkr) are elite viking warriors, naturally exclusively males, who are intertwined with the spirit of bears, and who are associated, often metaphorically, with the wearing of bear skins. Berserkir see bears as sacred and do not hunt them.
Berserkir are known for being able to reach alternate states of consciousness in order to fight, naturally and through exposure to extremely high level of androsterone from Blendingar, rather than through the use of any drugs or mushrooms. This results in violent expression of Óðr, leading to exceptional combat capabilities. Historically, Berserkir were described as entering apparently uncontrollable trances, as well as biting their wood shields to ultimately reach battle fury.
Berserkir are made, through combat and training, rather than born. Although nature versus nurture remains a source of debate when it comes to warriors.