Johann Gottfried Walther (18 September 1684 – 23 March 1748) was a German music theorist, organist, composer, and lexicographer of the Baroque era.
Walther was born at Erfurt, Electorate of Mainz and cousin of Johann Sebastian Bach.

Walther was most well known as the compiler of the Musicalisches Lexicon (Leipzig, 1732), an enormous dictionary of music and musicians. Not only was it the first dictionary of musical terms written in the German language, it was the first to contain both terms and biographical information about composers and performers up to the early 18th century. In all, the Musicalisches Lexicon defines more than 3,000 musical terms; Walther evidently drew on more than 250 separate sources in compiling it, including theoretical treatises of the early Baroque and Renaissance. The single most important source for the work was the writings of Johann Mattheson, who is referenced more than 200 times.