Johann Jakob Walther (1650 – 2 November 1717) was a German violinist and composer.
After the death of his patron in 1680 he became the Italian secretary at the elector's court in Mainz and was ordained a canon.
Alongside Biber and Westhoff, J.J. Walther is one of the most significant German violinists of the 17th century.
Besides a virtuoso technique including doublestops and arpeggios, his works display a wealth of formal devices, especially in the treatment of ostinato variations.
40 compositions are known, contained in two volumes: This article about a German composer is a stub.