berserker

Legendary Norse warrior whose frenzy in battle caused their transformation into a wolf or bear, made them howl and foam at the mouth (hence ‘to go berserk’), and granted immunity to sword and flame. Such warriors were an elite associated particularly with the raging war god Odin.

The berserker may be portrayed as a member of a king's bodyguard, or an individual antagonist picking quarrels to force combat. Part of the bravado consisted in fighting without armour, but the skin of a bear or wolf may have been worn as distinguishing garb, giving rise to their reputed ‘transformation’.

It has been suggested that ‘berserker fury’ may have been drug-induced, or represented an explanation for other psychological disturbance.