Shmelke of Nikolsburg (1726 Chortkiv, Galicia – April 28, 1778 Nikolsburg, Moravia) was one of the great early Chasidic Rebbes. Born Shmuel Horowitz (but commonly known by the diminutive "Shmelke"), he was the oldest son of Rabbi Tzvi Hirsh Horowitz of Chortkiv. A Levite, he traced his lineage back directly to the prophet Samuel who was also a Levite. In their early years, Shmelke and his brother Pinchas - who would also become a famous rabbi - studied Torah together. After traveling to Mezritch and meeting the great chasidic master Dovber of Mezeritch, they became his ardent followers.
After serving as rabbi in Ryczywół and Shineva, Shmelke was invited, in 1773, to become the rabbi of Nikolsburg in Moravia, where he served until 1778. On the first day of his being rabbi of Nikolsburg, Abraham Trebitsch a native of Nikolsburg reports him performing a miracle and bringing rain. It is told that his strong attachment to Chasidus angered many members of the community, which led to bitter quarrels that were quelled as a result of the personal intervention of Rabbi Elimelech of Lizhensk.
Shmelke established a major yeshiva that attracted numerous outstanding students. Among these were such luminaries as Rabbis Yaakov Yitzchak of Lublin, Menachem Mendel of Rimanov, Yisroel Hopsztajn, Mordecai Benet and Moshe Leib of Sassov.
The Nikolsburg Hasidic dynasty and the Boston Hasidic dynasty descend from him.