Joseph Hergenröther (September 15, 1824 - October 3, 1890), German theologian, was born at Würzburg in Bavaria.

He studied at Würzburg and at Rome. After spending a year as parish priest at Zellingen, near his native city, he went, in 1850, at his bishops command, to the university of Munich, where he took his degree of doctor of theology the same year, becoming in 1851 Privatdozent, and in 1855 professor of ecclesiastical law and history.

At Munich he gained the reputation of being one of the most learned theologians on the Ultramontane side of the Infallibility question, which had begun to be discussed; and in 1868 he was sent to Rome to arrange the proceedings of the Vatican Council. He was a stanch supporter of the infallibility dogma; and in 1870 he wrote Anti-Janus, an answer to The Pope and the Council, by Janus (Döllinger and J Friedrich), which made a great sensation. at the time. In 1877 he was made prelate of the papal household; he became cardinal deacon in 1879, and was afterwards made curator of the Vatican archives. He died in Rome on the 3rd of October 1890.

Hergenröther's first published work was a dissertation on the doctrine of the Trinity according to Gregory Nazianzen (Regensburg. 1850), and from this time onward his literary activity was immense. After several articles and brochures on Hippolytus and the question of the authorship of the Philosophumena, he turned to the study of Photius, patriarch of Constantinople, and the history of the Greek schism.

For twelve years he was engaged upon this work, the result being his monumental Pholius, Patriarch von Constantino pet. Sein Leben, seine Schriften und das griechische Schisma (3 vols, Regensburg, 1867-1869); an additional volume (1869) gave, under the title Monumenta Graeca ad Photium ... pertinentia, a collection of the unpublished documents on which the work was largely based.

Of Hergenröther's other works, the most important are:

• his history of the Papal States since the Revolution (Der Kirchenstaat seit der französischen Revolution, Freiburg i. B., 1860; Fr. trans., Leipzig, 1860)
• his great work on the relations of church and state (Katholische Kirche und christlicher Staat in ihrer geschichtlichen Entwickelung und in Beziehung auf Fragen der Gegenwart, 2 parts, Freiburg i. B., 1872; 2nd ed. expanded, 1876; Eng. trans., London, 1876, Baltimore, 1889)
• his universal church history (Handbuch der allgemeinen Kirchengeschichte, 3 vols, Freiburg i. B., 1876-1880; 2nd ed., 1879, etc.; 3rd ed., 1884-1886; 4th ed., by Peter Kirsch, 1902, etc.; French trans., Paris, 1880, etc.)

He also found time for a while to edit the new edition of Wetzer and Welte's Kirchenlexikon (1877), to superintend the publication of part of the Regesta of Pope Leo X (Freiburg i. B., 1884-1885), and to add two volumes to Hefele's Conciliengeschichte (ib., 1887 and 1890).