John Humbird Duffey Jr. (March 4, 1934 – December 10, 1996) was a Washington D.C. based bluegrass musician. Duffey was born in Washington, D.C., and lived nearly all his life in the Washington D.C. area. He graduated from Bethesda-Chevy Chase High School in suburban Maryland. Duffey learned to play the mandolin, dobro, and guitar, in addition to his tenor singing voice. He founded two of the most influential groups in bluegrass, The Country Gentlemen and The Seldom Scene. His tastes and sources were eclectic, often raiding folk song books and Protestant hymnals for material. He embraced the music of Bob Dylan and his style of playing was rock and jazz-inflected. In the late 1950s and the 1960s, he also increasingly began working as a session musician to supplement his income.