German historical scholar, prominent Roman Catholic theologian who refused to accept the doctrine of papal infallibility decreed by the first Vatican Council (Vatican Council, First) (1869–70). He joined the Old Catholics (Old Catholic church) (Altkatholiken), those who separated from the Vatican after the council but believed they maintained Catholic doctrine and traditions.

Ordained in 1822, he became professor of canon law and church history at Munich in 1826. From 1835 he was a member of the Bavarian Royal Academy of Sciences and served as its president from 1873. Though he lost his professorship in 1847 for protesting the dismissal of four colleagues by King Ludwig I of Bavaria, he was given posts that made him second to the archbishop of Munich and was reappointed professor of church history in 1849. Döllinger was a brilliant scholar whose embrace of modern historical criticism and whose belief in religious freedom brought him into conflict with papal policy. His opposition to the Ultramontanists, those who supported papal infallibility, led to his designation as the leader of the antipapal party in Germany.

In 1869 Döllinger wrote a series of articles, later enlarged and published as Der Papst und das Konzil (1869; The Pope and the Council), under the pen name Janus. This book, which criticized the Vatican Council and the doctrine of infallibility, immediately was placed on the Vatican's Index of Forbidden Books.

After his refusal to accept the doctrine of papal infallibility, Döllinger was excommunicated (1871) but was elected rector of Munich University in the same year. Döllinger and his colleagues, all excommunicated, held a congress to oppose the council's dogmas at Munich on Sept. 22, 1871; it was attended by 300 Old Catholics and Eastern Orthodox, Anglican, and Lutheran sympathizers. A committee, of which Döllinger was a member, drew up a doctrinal basis and a program for separate organization. According to Döllinger, it was the vocation of the Old Catholic communion to protest the Vatican dogmas, to support a Catholic church free from error, and to reunite Christendom.