In the Guiness Book of Music Facts & Feats, the record for "Most Prolific Composer" goes to Georg Philip Telemann, who died on today's date in 1767 at the age of 86.
Telemann's output is staggering. Of Bach's cantatas, some 200 or so survive, but Telemann's number 1400. He also wrote 125 orchestral suites, 125 concertos, 130 trios, 145 pieces for solo keyboard, and about 50 operas.
Here Jordi Savall leads Hespèrion XXI in a performance of Telemann's Concerto for recorder, bassoon, strings & continuo in F major, TWV 52
Thank you, Composer's Datebook.