Four Jacks and a Jill is a South African folk rock ensemble that gained international prominence in the late 1960s. The band's distinctive sound blends traditional folk elements with pop, underscored by the unique vocals of lead singer Glenys Lynne. Their most notable contribution to music history is the hit single "Master Jack," which reached the U.S. Billboard Hot 100 in 1968, a rare achievement for South African bands of the era. The group's lineup, unusual in maintaining the same members throughout its active years, is also noteworthy in the landscape of 1960s rock music.