A warrior in a frenzied battle-state considered invulnerable.

The berserkr was a warrior type in Old Norse society known for entering a violent and uncontrollable frenzy in battle, called berserksgangr. The state was considered magical and linked to Óðinn as lord of battle-ecstasy.

Historical and literary sources describe berserkers fighting without armour, biting their shields, and being immune to sword and fire. They served as war-leaders' personal guards and were greatly feared by opponents.

Attestations

Ynglinga saga 6
Snorri describes Óðinn's warrior retinue of berserkers.