The Toccata and Fugue in D minor, BWV 565, is a piece of organ music written, according to its oldest extant sources, by Johann Sebastian Bach. The piece opens with a toccata section, followed by a fugue that ends in a coda. It is one of the most famous works in the organ repertoire.
Scholars differ as to when it was composed. It could have been as early as c.1704 (when the presumed composer was still in his teens), which would be one explanation for the unusual features; alternatively a date as late as the 1750s has been suggested (Bach died in 1750). To a large extent the piece conforms to the characteristics deemed typical for the north German organ school of the baroque era with divergent stylistic influences, such as south German characteristics, described in scholarly literature on the piece.
Despite a profusion of educated guesswork there is not much that can be said with certainty about the first century of the composition's existence other than that it survived that period in a manuscript written by Johannes Ringk. The first publication of the piece, in the Bach Revival era, was in 1833, through the efforts of Felix Mendelssohn, who also performed the piece in an acclaimed concert in 1840. Familiarity with the piece was enhanced in the second half of the 19th century by a fairly successful piano version by Carl Tausig, but it was not until the 20th century that its popularity rose above that of other organ compositions by Bach. That popularity further increased, due for example to its inclusion in Walt Disney's Fantasia, until this composition came to be considered the most famous work in the organ repertoire.
A wide, and often conflicting, variety of analyses has been published about the piece: for instance in literature on organ music it is often described as some sort of program music depicting a storm, while in the context of Disney's Fantasia it was promoted as absolute music, nothing like program music depicting a storm. In the last quarter of the 20th century scholars like Peter Williams and Rolf-Dietrich Claus published their studies on the piece, and argued against its authenticity. Bach scholars like Christoph Wolff defended the attribution to Bach. Other commentators ignored the authenticity doubts or considered the attribution issue undecided. No edition of the Bach-Werke-Verzeichnis listed the Toccata and Fugue among the doubtful works, nor does its entry on the website of the Bach Archiv Leipzig even mention alternative views on the attribution issue.