Ephraim ben Isaac ben Abraham of Regensburg (Hebrew: אפרים בן יצחק מרגנסבורג; c. 1110 – 1175) also sometimes called Ben Yakir, was a 12th-century German tosafist and liturgical poet who was known for his keen intellect, his numerous piyyutim and for controversy refusing to recognize any post-Talmudic authority.