John Alexander McGlinn III (September 18, 1953 – February 14, 2009) was an American conductor and musical theatre archivist. He was one of the principal proponents of authentic studio cast recordings of Broadway musicals, using original orchestrations and vocal arrangements. 　　John Alexander McGlinn III was born in Bryn Mawr, Pennsylvania, and was raised in Gladwyne, Pennsylvania. A self-taught pianist, he studied music theory and composition at Northwestern University, graduating in 1976.