T. was born on 21 March 1895 in New York, America. His parents were Bessie and Boris Thomashefsky. He completed public school and a five-class high school. He learned art painting at Columbia University, and Yiddish studies with a tutor.

As a child he acted in his father's play "Dos pintele yid" and in Goldfaden's "Di kishufmakherin", ("Heyse bobkelen").

In 1913 Sh. was a manager of his father's visit to Europe, and in 1917 participated together with his father and Kessler in Lillian's "Kinder kumt aheym", in which he alone wrote a role for himself. Later, as an assistant director for his father, he traveled with him to Argentina and Brazil, where he had performed as a "fat comic", acting afterwards and managed his father in Toronto  as he also did during his tour across America with the play "Shteyger-protses" and in the Metropolitan Opera in Philadelphia. In 1929-30 he acted in Gabel's Public Theatre. In 1931-32 he was manager in his father's Lyric Theatre, and in 1932 in his father's Gaiety Theatre.

On 7 February 1920 there was staged T.'s play "Parlor, Floor and Basement, a comedy in 3 acts, music by Milton and Harry Thomashefsky". He also wrote an English sketch. On 10 February 1931 in New York's Selvin? Theatre there was staged his English verse from his father's operetta, "Di khznte", also named "Di singing rabey (The Singing Rabbi)".

T. also draws plans for decoration and caricature for English journals.
 

M. E.

• Bessie Thomashefsky -- "Meyn lebens-geshikhte", pp. 228-29.

• Jacob Kirschenbaum -- "Neye pnim'er oyf unzer bihne, "Morning Journal", N. Y., 4 February 1927.