Zemach Shabad (Polish: Cemach Szabad, Russian: Цемах Шабад, Tsemakh Shabad) (February 5, 1864, Vilnius, Russian Empire (now Lithuania) — January 20, 1935, Vilnius) was a Jewish doctor and social and political activist. He was a member of the Senate (parliament) of the Second Polish Republic (1928) and a co-founder and vice-president of the YIVO (Institute for Jewish Research).