Did Vikings wear horned helmets?
No. There is no archaeological evidence whatsoever that Viking Age warriors wore horned helmets, and the image is a nineteenth-century invention.
What the evidence actually shows. Only one reasonably complete helmet from the Viking Age has ever been found — the Gjermundbu helmet, discovered in Norway in 1943. It is a simple rounded iron cap with a spectacle-like eye guard. No horns. Helmet fragments from other sites are consistent with the same design.
Why horns would be actively stupid in combat: they provide a handle for an opponent to grab and twist, they catch on branches and rigging, they add weight high on the head, and they would deflect a downward blow into the skull rather than away from it. Practical armour is smooth for good reason.
Where the myth came from. Two strands combined in the 1800s:
Romantic nationalism. Scandinavian artists and writers of the National Romantic movement were reimagining a heroic Norse past, and horned headgear looked suitably dramatic.
Opera. Costume designer Carl Emil Doepler created horned helmets for the 1876 premiere of Wagner's Der Ring des Nibelungen at Bayreuth. The production was enormously influential, and the image spread through popular culture and never left.
A genuine confusion underlies it. Horned helmets do exist in Northern European archaeology — but from the Bronze Age, some 2,000 years before the Vikings. The Veksø helmets from Denmark date to around 900 BC and appear ceremonial rather than military. Nineteenth-century antiquarians conflated these with the much later Viking Age.
Some depictions on artefacts show horned or bird-headed figures, but these are interpreted as ritual or mythological imagery — possibly Odin-related — rather than everyday equipment.
Most Vikings probably wore no helmet at all. Iron was expensive, and a leather cap or nothing was likely the norm outside the wealthy.