Final answer:
The Grimm brothers, Jacob and Wilhelm, are known for their collection of German fairy tales and their significant work on a German dictionary. Their last name is Grimm, and they were significant contributors to the field of Romantic nationalism, aiming to preserve the German cultural identity.
Step-by-step explanation:
The last name of the two brothers from Germany who became famous for their collections of German fairy tales is Grimm. The brothers, Jacob and Wilhelm Grimm, were noted philologists and their work in collecting and publishing these tales was foundational. Their most famous publication included tales such as Sleeping Beauty and Cinderella, which became widely recognized in American culture through Walt Disney's animated films.
Moreover, the Grimm brothers were key figures in the Romantic nationalism movement. They endeavored to capture the essence of what it meant to be German through their collections of tales, songs, and linguistic work, including a comprehensive German dictionary. Their passion for preserving the German spirit was partly motivated by a fear that these cultural identities were at risk of being lost to modernity.