Jan Gotlib Bloch, Polish theorist and activist (d. 1902)
Jan Gotlib (Bogumił) Bloch (Russian: Иван Станиславович Блиох or Блох) (July 24, 1836 – January 7, 1902) was a Polish banker and railway financier who devoted his private life to the study of modern industrial warfare. Born Jewish and a convert to Calvinism, he spent considerable effort to opposing the prevalent antisemitic policies of the Tsarist government, and was sympathetic to the fledgling Zionist movement.

Bloch had studied at the University of Berlin, worked at a Warsaw bank and then moved to St. Petersburg, capital of the Russian Empire (which governed much of the Polish lands at the time). There, he took part in the development of the Russian Railways, both in financing the construction of new railways and in writing research papers on the subject. He founded several banking, credit and insurance companies. In 1877 he was appointed a member of the Russian Finance Ministry's Scientific Committee.

Bloch was married to Emilia Julia Kronenberg h. Koroniec (1845-1921), the granddaughter of Polish banker Samuel Eleazar Kronenberg and niece of Leopold Stanislaw Kronenberg; the Kronenberg and Bloch families had often been in competition with each other in several 19th century Polish businesses.