Sigmund Gottfried Spaeth (April 10, 1885 – November 11, 1965) was an American musicologist who sought to de-mystify classical music for the general public. His extensive knowledge of both the classical repertoire and popular song enabled him to trace the melodies of current hits back to earlier sources; this talent garnered him fame as the "Tune Detective," a role he played as an entertainer, educator, and as an expert witness in cases of plagiarism and infringement of copyrighted music.

Spaeth wrote over thirty books on both popular and classical music. He promoted his ideas about music and music appreciation with vaudeville appearances, books and magazine articles, lectures, and radio and television programs.

A serious academic, an athlete and a musician, Spaeth described himself as a "writer, broadcaster, lecturer, composer, arranger and general showman and entertainer."