Anti-Jewish writer of the sixteenth century; born at Holtwick in Westphalia in 1491; died at Cologne May 21, 1542. He was the son of a priest, and became one of the chiefs of the Dominican party in Cologne. Ortuin was a rabid Jew-hater, and wrote much against the Jews. He took sides with Pfefferkorn during the latter's controversy with Reuchlin, and with the assistance of Victor von Karben, a baptized Jew, wrote "De Vita et Moribus Judæorum" (1504); he afterward translated it into German. This book is a fanatical diatribe against Jews and Judaism. Ortuin translated Pfefferkorn's anti-Jewish writings into Latin.

Bibliography: Grätz, Gesch. ix., passim;
L. Geiger, Reuchlin's Leben und Werke, in Ulr. Hutteni Opera, iii. 359-361, Leipsic, 1871;
idem, in Allg. Deutsche Biographic, ix. 600-602;
Kohut, Gesch. der Deutschen Juden, p. 466.D. A. M. F.