Hans Christian Andersen, 1805 -1875 was an acclaimed Danish author. Although he wrote in several literary genres, it was his writing for children that brought him lasting fame. Most of these works were fairy tales, others are fables. Andersen's stories often contain morals, and many are sad or tinged with sadness. Modern adaptations often obscure the misery in Andersen's original writing (the Little Mermaid, for example, dies in the original story but lives 'happily ever after' in Disney's adaptation.
The expressions 'the emperor has no clothes/isn't wearing any clothes' from The Emperor's New Clothes and 'ugly duckling' from The Ugly Duckling have entered the English language.