Final answer:
The last name of the famous German brothers who collected fairy tales is Grimm. The Brothers Grimm were known for their work on German folk tales and a comprehensive German dictionary.
Step-by-step explanation:
The last name of the two brothers from Germany who became famous for their collection of fairy tales is Grimm. The Brothers Grimm, Jacob and Wilhelm, were notables as expert philologists and as the publishers of the first definitive collection of German folk tales. They were dedicated to preserving what they believed to be the spiritual essence of the German people, which they found in old folk songs, the German language, and traditional stories.
Through their work, they gathered stories such as Sleeping Beauty and Cinderella, which many might recognize from their adaptations as animated films by Walt Disney. Aside from their fairy tale collections, the Grimm brothers also began compiling a comprehensive German dictionary to capture the etymology of the German language, although they did not live to see its completion.