Thomashefsky is a surname that is a variant of the Polish masculine surname Tomaszewski or the Russian Tomashevsky. Notable people with the surname include:
Bessie Thomashefsky (1873–1962), Ukrainian-born Jewish American singer, actress and comedian Boris Thomashefsky (1868–1939), Ukrainian-born Jewish American singer and actor
See also
Michael Tilson Thomas (1944–2026), Jewish American conductor, composer and pianist. The surname was changed from Thomashefsky by his father, Ted, who was the son of Boris and Bessie.