Which Grimm fairy tale features a wild man named 'Iron Hans'?

The Grimm fairy tale featuring a wild man named “Iron Hans” is “Iron Hans,” also commonly translated as “Iron John.”

The story appears as tale 136 in the Brothers Grimm collection. A king’s hunters discover an enormous, iron-skinned wild man living in a forest pool and imprison him in an iron cage. Years later, a prince frees him with a key hidden beneath the queen’s pillow and follows him into the forest.

Iron Hans becomes a mysterious helper who guides the prince through trials involving a magical well, golden objects, disguises, and battles. The prince eventually wins recognition and a royal marriage, while Iron Hans is released from his own enchantment. The tale is classified as ATU 502, “The Wild Man as Helper.”

“Iron John” is the more familiar English title of the Grimm story, while “Iron Hans” preserves the German name Eisenhans more closely. It should not be confused with the television series Grimm episode also titled “Iron Hans.”