Leo Motzkin (also Mozkin; 1867 – 7 November 1933) was a Russian Zionist leader. A leader of the World Zionist Congress and numerous Jewish and Zionist organizations, Motzkin was a key organizer of the Jewish delegation to the 1919 Paris Peace Conference and one of the first Jewish leaders to organize opposition to the Nazi Party in Germany.
Leo Motzkin was born in the town of Brovary, near the city of Kiev in Ukraine, then a part of the Russian Empire. He was raised and educated according to the culture and traditions of the Jewish community. Motzkin had witnessed the 1881 anti-Jewish pogrom in Kiev but escaped to Berlin, the capital of Germany. He was accepted into the University of Berlin at the age of 16, after graduating from high school. Studying Sociology and Mathematics, Motzkin continued on to pursue doctoral studies. At the university, Motzkin helped found the Russian Jewish Academic Association in 1887 and soon became a full-fledged activist in the Zionist movement.
Motzkin participated in the First Zionist Congress in 1897 and became close to the Zionist leader Theodore Herzl, who sent him on a mission to Palestine to investigate the problems of the Jewish community; contrary to other leaders such as Baron Rothschild and Hovevei Zion, Motzkin favored co-operation with the Ottoman Empire for Jewish interests. Motzkin represented the "Democratic Fraction" at the Fifth Congress in 1901.