The Stanley Brothers were a famous American bluegrass duo, consisting of siblings Carter Stanley and Ralph Stanley. They gained popularity in the mid-20th century for their unique harmonies and traditional mountain music style. Their work significantly influenced the bluegrass genre, and they are known for songs like "Man of Constant Sorrow" and "Pretty Polly." The brothers began performing in the 1940s and were part of the Grand Ole Opry for several years. They also contributed to the development of the Stanley Style of bluegrass music, characterized by high lonesome vocals and intricate instrumentation. Their legacy continues to inspire musicians today.