Wilhelm Friedemann Bach (November 22, 1710 – July 1, 1784) was the eldest, and by common repute the most gifted son, of Johann Sebastian Bach; a famous organist, a famous improvisor, and a complete master of counterpoint.

Unlike the rest of the family, he was a man of idle and dissolute habits, whose career was little more than a series of wasted opportunities. Born in Weimar and educated at Leipzig, he was appointed in 1733 organist of St. Sophia's Church at Dresden, and in 1747 became musical director of the Liebfrauenkirche at Halle. The latter office he was compelled to resign in 1764, and thenceforward he led a wandering life until, on the 1st of July 1784, he died in great poverty at Berlin, aged 74.

His compositions, very few of which were printed, include many church cantatas and instrumental works, of which the most notable are the fugues, polonaises and fantasias for clavier, and an interesting sestet for strings, clarinet and horns. Several of his manuscripts are preserved in the Royal library at Berlin; and a complete list of his works, so far as they are known, may be found in Eitner's Quellen Lexikon.

He is not to be confused with Wilhelm Friedrich Ernst Bach, his nephew, also a composer.