Berserks—meaning “bear-shirts” or “bare-shirts”—were the god Odin’s warriors. Foot soldiers in the forefront of battle, they “wore no armor and were as mad as dogs or wolves, bit their shields, were as strong as bears or bulls. They killed other men, but neither fire nor iron could kill them. That is called going berserk,” explained the thirteenth-century Icelandic writer Snorri Sturluson. Sometimes the “bear-shirts” wore shirts of wolf skin instead.