Picture a Viking, and you may see a horned helmet. Yet the few Viking Age helmets found have no horns, and writings from that time never mention horns.
The horned look began in the 1800s. Richard Wagner's operas, based on the Vikings' old Norse legends, made it popular by putting horns and wings on Viking helmets on stage.
Historians have debunked it many times, but it lives on because the image is so striking.