Katznelson Isaak (5 March 1926, Bobruisk) — violinist.

In 1942–43, Isaak Katznelson played in the orchestra of the Musical Comedy Theatre in Kyzyl-Orda. From 1946 to 1950, he studied at the M. M. Ippolitov-Ivanov Higher School of Music (Moscow). In 1957, he graduated from the Latvian State Conservatoire (class of Prof. J. Targonskis).

In 1950–51, he worked in the Moscow State Variety Ensemble. In 1952, he moved to Riga. In 1952–54, he was a member of the orchestra of the Riga Operetta Theatre, in 1954–56 played in the orchestra of the Riga Circus, in 1956–61 worked with the cinema orchestra “Riga” under the Latvian Philharmonic, and in 1961–86 performed in the Symphony Orchestra of Latvian Radio.

From 1960, he taught at the P. Jurjans Music School, and from 1964, at the Emīls Dārziņš Music School. He later emigrated to the United States and settled down in New York.