Mordechai Yosef Leiner of Izbica (מרדכי יוסף ליינר) known as "the Ishbitzer" (Yiddish: איזשביצע, איזביצע Izhbitze, Izbitse, Ishbitze) (1801-1854) was a rabbinic Hasidic thinker and founder of the Izhbitza-Radzyn dynasty of Hasidic Judaism. He is best known for his work Mei Hashiloach.