Klotz is a family of violin makers. Members of the Klotz (or Kloz) family have made violins in Mittenwald, Germany from the mid-17th century to the present. The Klotz family taught other families of the village the violin trade, and Mittenwald prospered and became well known for its violins. In A Dictionary of Music and Musicians 1900, the contributor Edward John Payne writes: "Nine-tenths of the violins which pass in the world as 'Stainers' were made by the Klotz family and their followers." In 1856, the Bavarian government founded a school in Mittenwald to continue the violin trade. Dictionaries of violin makers list more than 25 artisans by this name.
Matthias I (1656–1743) founded the Mittenwald school of violin making after study with Giovanni Railich in Padua from 1672-1678, Jacob Stainer and Nicolo Amati. He has been criticized for exercising insufficient skill or care in the selection of his wood. Typical labels:Mattias Klotz Geigenmacher zu Mittenwald an der Iser 1697
Mathias Klotz Lauten und Geigenmacher in Mittenwald an der Iser Anno 1695
Mathias Kloz Lautenmacher. A label of the family  in Mittenwalt Anno 1725.
Instruments by Sebastian I (1696–1768) are probably the most admired among the many existing examples by this family. Some instruments which have been identified as Sebastian's work bear his father's label. Typical labels:Sebastian Klotz in Mittenwald an der Iser 1734
Sebastian Kloz, in Mittenwald, an 1743
Seb. G. Kloz in Mittenwald, 1732
Joseph (1743–1819), son of Sebastian, worked in a manner similar to that of his father.
The quality of their instruments varies enormously, and many inferior, unauthentic examples have labels bearing the Klotz name.