2015 marks the 50th anniversary of the discovery of P.D.Q. Bach by Peter Schickele. (Strictly speaking, the above isn’t P.D.Q.B., though it is from one of the early albums.)
Here’s another approach to Beethoven. (Via the Borderline Boy.)
1965 also saw The Baroque Beatles Book of Joshua Rifkin.
According to the liner notes of a reissue, Schickele was the first choice to write the arrangements, but he had just been signed to a different label, so Rifkin got the job. Incidentally, Rifkin sang in the first performance of P.D.Q. Bach’s “Iphigenia in Brooklyn.” A few years later, he would jumpstart the ragtime revival with his Scott Joplin recordings.
Here’s a more modern approach to the Beatles.
Glorieux’s Beatle recordings, which range stylistically from Bach to Bartok, are out of print, but you can find them on YouTube.