CONRAD OF MARBURG (c. 118o-1233), German inquis itor, born probably at Marburg, and educated at the university of Bologna. It is not certain that he belonged to any order, although he has been claimed both by the Franciscans and the Dominicans. In 1214 he was commissioned by Innocent III. to arouse interest in the proposed crusade, and during his mission of reforming con vents he came to occupy, in 1226, a position of influence at the court of Louis IV., landgrave of Thuringia. He became confessor to the landgrave's wife, St. Elizabeth of Hungary (q.v.), and exercised the landgrave's rights of clerical patronage during his absence on crusade. In 1227 he was employed by Pope Gregory IX. to extirpate heresy in Germany, to denounce the marriage of the clergy, and to visit the monasteries. In 1233 he accused Henry II., count of Sayn, of heresy. An assembly at Mainz of bishops and princes declared Henry innocent, but Conrad demand ed that this sentence should be reversed. As he rode from Mainz he was murdered near Marburg, on July 3o, 1233. His Epistola ad papam de miraculis Sanctae Elisabethae was published at Cologne in 1653. Conrad is known to English readers through Kingsley's Saint's Tragedy, in which he is a prominent character.
See E. L. T. Henke, Konrad von Marburg (Marburg, 1861) ; B. Kal ter, Konrad von Marburg and die Inquisition in Deutschland (Prague, 1882) ; A. Hausrath, Der Ketzermeister Konrad von Marburg (Leipzig, 1883) ; Michael, Gesch. des deutschen Volkes, vol. ii. (Freiburg, 1899).