P. D. Q. Bach is a fictional composer created by Peter Schickelem (1935-2024). Schickele studied composition at Juilliard and was an accomplished bassoonist. His wrote an awful lot of (brilliant) parodies of classical music tributed to the name P. D. Q. Bach eg the 1712 Overture, The Civilian Barber, etc. Read more about him:

NYTimes on Peter Schickele

The Boston Musical Intelligencer Article about P. Schikele