Johann Jakob Walther (1650 – 2 November 1717) was a German violinist and composer.
All the known facts of his life and activity are from Musikalischen Lexikon by Johann Gottfried Walther (Johann Sebastian Bach's cousin), a dictionary which first appeared in 1732. He was born in Witterda bei Erfurt. Between 1670 and 1674 he is said to have remained a violinist in the orchestra of Cosimo III of the Medicis in Florence. From 1674 he was concertmaster at the court of Dresden. 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. He died in Mainz.
Alongside Biber and Westhoff, J.J. Walther is one of the most significant 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: