Thamer, Theobald a theological agitator in the time of the Reformation in Germany. He was a native of Rossheim, in Alsace, and studied at Wittenberg under Luther and Melancthon, taking the degree of master in 1539. He had been supported while a student by the landgrave Philip of Hesse, who wished to train the youth for service in his employment; and after a time spent as professor of theology at Frankfort-on-the-Oder, Thamer responded to the landgrave's call and became professor and preacher at Marburg. To the chagrin of his prince, however he showed himself a rigid Lutheran, whose influence was directly opposed to the compromises which Philip hoped to bring about between the contending evangelical factions. In the Smalcald war Thamer served in the field as a chaplain. He there saw reason to lose faith in the cause of the Reformation, and to discover the occasion of all the troubles of the situation in the Lutheran doctrine of justification; and on his return to Marburg he assailed that doctrine in the pulpit and the lecture room. He emphasized the ethical side of Christianity, and separated it from the doctrinal side, thus gradually coming to occupy rationalistic ground. The government dealt with him mildly, at first transferring him to Cassel, and then entering into extended negotiations with him; but as he persisted in disturbing the peace of the Church, he was dismissed from all his offices Aug. 15, 1549. He secured a position as preacher at Frankfort-on-the- Main, whence he continued to asperse the Lutheran doctrines, until he exhausted the patience of his new patrons. He then turned to the landgrave with the offer to defend his views before competent judges, and he actually visited Melancthon, Gresser, Schnepf, and Bullinger. No settlement was reached in their discussions, however, and Thamer was dismissed from the dominions of Hesse. He went to Italy and in 1557 entered the Romish Church. In time he was made professor of theology at Freiburg. He died May 23, 1569. See Neander, Theobald Thamer, etc. (Berl. 1842); id. Hist. of Dogmas, p. 631; Pestalozzi, Bullirger, p. 461 sq.; Schenkel, Wiesen d. Protestantismus, 1, 144 sq.; Hochhuth, De Th. Thameri Vita et Scriptis (Marb. 1858), and the article in Niedner's Zeitsch. hist. Theologie, 1861, No. 2. Herzog, Real-Encyklop. s.v.