John Carl Hendricks, known professionally as Jon Hendricks, was an American jazz lyricist and singer. He is one of the originators of vocalese, which adds lyrics to existing instrumental songs and replaces many instruments with vocalists, such as the big-band arrangements of Duke Ellington and Count Basie. He is considered one of the best practitioners of scat singing, which involves vocal jazz soloing. Jazz critic and historian Leonard Feather called him the "Poet Laureate of Jazz", while Time dubbed him the "James Joyce of Jive". Al Jarreau called him "pound-for-pound the best jazz singer on the planet—maybe that's ever been".

Originating in vocal jazz, scat singing or scatting is vocal improvisation with wordless vocables, nonsense syllables or without words at all. In scat singing, the singer improvises melodies and rhythms using the voice solely as an instrument rather than a speaking medium. This is different from vocalese, which uses recognizable lyrics that are sung to pre-existing instrumental solos.