Johann Friedrich (May 5, 1836–1917), was a German theologian. He was prominent as a leader of the Old Catholics.
He was born at Poxdorf in Upper Franconia, and was educated at Bamberg and at the University of Munich. He was ordained a Catholic priest in 1859. In 1865, he was appointed extraordinary professor of theology. In 1867, he was appointed to the Academy of Sciences. He was a pupil of Ignaz von Döllinger.
In 1869 he went to the Vatican Council as secretary to Cardinal Hohenlohe, and took an active part in opposing the dogma of papal infallibility, notably by supplying the opposition bishops with historical and theological material. He left Rome before the council closed.
A sentence of excommunication was passed on Friedrich in April 1871, but he refused to acknowledge it and was upheld by the Bavarian government. He continued to perform ecclesiastical functions and maintained his academic position, becoming an ordinary professor in 1872. In 1874, he inaugurated the Old Catholic theological faculty at the University of Bern and lectured there for a year. In Bavaria, in 1882, the Minister of Public Worship, yielding to ultramontane pressure, transferred him from his chair in theology to the philosophical faculty as professor of history. By this time he had to some extent withdrawn from the advanced position which he at first occupied in organizing the Old Catholic Church, for he was not in agreement with its abolition of enforced celibacy.
Friedrich was a prolific writer; among his chief works are: