This instrument from Stradivari’s mature production period is named after one of its former owners, the popular American comedian, vaudevillian and actor Jack Benny (1894–1974). Mr. J. Benny’s real name was Benjamin Kubelsky, but it seems that he was asked by the Czech violinist and composer Jan Kubelík (1880–1940) to give it up, since the latter felt an entertainer with a name similar to his own would damage his reputation.
More information: Antonio Stradivari Set 1, Volume 4, Page 194