Margo Thunder is an American soul and R&B singer, best known for her work in the 1960s and 1970s. Thunder's musical style is characterized by its blend of soulful vocals and rhythm and blues influences, making her a prominent figure in the genre. She gained recognition as part of the group 9.9, with their single "All of Me for All of You" charting on the Billboard Hot 100. In her solo career, she had a hit with "Expressway to Your Heart", showcasing her powerful vocal abilities and her knack for delivering expressive performances.