The Mills Brothers were an influential American jazz and pop vocal group active from the 1920s to the 1990s. Consisting of four brothers - John, Herbert, Harry, and Donald Mills - they were known for their unique style of vocal harmonization, often mimicking instruments with their voices. They gained significant popularity with hits like "Paper Doll" and "You Always Hurt the One You Love," making substantial contributions to the development of vocal group music. Through their smooth, harmonious style and innovative vocal techniques, the Mills Brothers left a lasting impact on both jazz and pop music genres.