Amos Leon Thomas Jr. (1937–1999), known professionally as Leon Thomas, was a groundbreaking American jazz and blues vocalist celebrated for his distinctive free jazz singing style in the late 1960s and 1970s. He became renowned for his "bellowing glottal-stop" technique, often incorporating a powerful, ritualistic yodel—a style he called "soularphone"—which significantly influenced artists like Bobby McFerrin. After an early career that included a brief stint with the Count Basie Orchestra, Thomas rose to prominence working with avant-garde saxophonist Pharoah Sanders, most famously on the iconic 1969 song "The Creator Has a Master Plan."
Throughout the 1970s, he released critically acclaimed solo albums for Flying Dutchman and performed with artists such as Freddie Hubbard and Carlos Santana, earning him the moniker "the John Coltrane of jazz vocalists" for his innovative fusion of scat, vocalese, and spiritual exploration. Thomas viewed music as a vital means of social commentary, embodying a deeply reflective approach to his art. His "kosmigroov" recordings found a new audience in the 1990s, cementing his legacy before he passed away on May 8, 1999.