Berserkers were Norse soldiers known for wild violence.

Evidence

These are the fighters called berserkers. … Berserker is an Icelandic word for a soldier wearing a shirt made of bearskin, and the word ‘berserk’ even today is synonymous with wild, destructive violence. — Neil MacGregor, A History of the World in 100 Objects, 964

Categorization

• corroborated: 2 independent passages support this claim — Neil MacGregor, A History of the World in 100 Objects, 964