Johann Sebastian Bach
From Tardis Wiki, the free Doctor Who reference
Johann Sebastian Bach was a German composer.
The Fourth Doctor played out Badinerie, Orchestral Suite No. 2 in B minor on his reed flute. (TV: The Power of Kroll)
After fixing his TARDIS' chameleon circuits and turned into a organ, the Sixth Doctor played out the opening notes of Toccata and Fugue in D minor. (TV: Attack of the Cybermen)
The music playing at 3W is "Air on the G String" when the Twelfth Doctor and Clara Oswald were "browsing". (TV: Dark Water)