FESSLER, Joseph. — Bishop, historian, and canonist, b. at Lochau (Vorarlberg) on 2 Dec. 1813; d. at St. Pölten (near Vienna) on 25 Apr. 1872. Ordained priest in 1837, he taught ecclesiastical history and canon law at the Seminary of Brixen from 1838; then, from 1852, at the University of Vienna. Auxiliary bishop and vicar general for Vorarlberg in 1862, imperial ambassador to Rome for the Concordat (1863), bishop of St. Pölten (1864), secretary of the Vatican Council (1869–70).
His most important work is: *Institutiones Patrologiae* (2 vols., Innsbruck 1850–51; 2nd ed. ed. B. Jungmann [2 vols., 1860–61]; other notable works include: *Das kirchliche Bücherverbot* (Vienna 1869); *Der canonische Prozess* (Vienna 1860); *Das letzte und nächste allgemeine Konzil* (Freiburg im Br. 1869); *Sammlung vermutlicher Schriftsteller über Kirchengeschichte und Kirchenrecht* (1869); *Die wahre und falsche Unfehlbarkeit der Päpste* (Vienna 1871); *Das vaticanische Concil, dessen Auszüge* (1871).