Oliver Sain was an influential American saxophonist, songwriter, and record producer predominantly active in the 1960s and 1970s. His music blended jazz, rhythm and blues, and soul, creating a distinctive sound that was foundational to the St. Louis music scene. Sain's most significant work includes the hit "Don't Mess Up a Good Thing," and his production and writing for artists like Fontella Bass and Little Milton. His impact on the music industry and contributions to the development of soul and R&B music are highly regarded in music history.