Viking Queen

Queen Astrid by the American illustrator N.C. Wyeth (1882–1945). Wyeth did this Wagnerian illustration for the book The World Of Music - Song Programs for Youth (1938).

The White Company

The White Company by the great American illustrator N.C. (Newell Convers) Wyeth (1882–1945). This was the cover for the historical adventure novel by Arthur Conan Doyle which is set during the Hundred Years' War. Maybe it should be mentioned that the real mercenary company with this name never wore white white clothes, the name refered to "white" armour, i.e. plate armour.
But anyway Wyeth painted an impressive bunch of cutthroats.

Sturdy Knights

An illustration of the book The Boy's King Arthur (1922) by N.C. (Newell Convers) Wyeth, one of America's greatest illustrators (1882–1945).

Unlike the 19th century artists historical accuracy was no objective for Wyeth. He was aware that history always would be a construction. So he painted two bullish, powerful knights wearing their armor like a skin.

Horned Helmets

Even though there are lots of history paintings with Vikings or Germanic warriors wearing horned helmets it is sure that this is a pure invention. Celtic warriors or some Etruscans may have had helmets with horns or wings. The few depictions in Northern Europe belong to older times, the Bronze Age, and are probably showing helmets for ceremonial purposes.

Illustration by N.C. Wyeth for the Arthur Conan Doyle story "The First Cargo", published in Scribner's Magazine, December 1910.

Germanic warriors with horned or winged helmets were a typical invention of 19th century Romanticism, probably because they look so barbarian and exotic. The creation became popular when costume designers used the idea for the heroes and gods in Wagner’s operas.

Later this pure fantasy-invention became so popular that even Danes of today put on these helmets to look like real Vikings. So it’s at least a nice example how the iconography of history painting influenced reality.