Gropper, Johann, a German Romanist divine, was born at Soest in 1591, became successively canon of Cologne, provost of Bonn, and archdeacon and provost of St. Gereon of Cologne. He convoked a provincial synod in 1536 with the intention of effecting some reforms, and was afterwards sent by Charles V to the religious assembly of 1541 at Regensburg ;, he is even said to have flamed the Interim which was there decided on. In 1548 he went to Soest, to reform the churches of that place agreeably to the Interim. In 1551, on the occasion of the reopening of the Council of Trent, the pope called him to Rome for the purpose of consulting with him. Here he died, March 12, 1558. Gropper belonged to the class of milder Romanists who, at the time of the Reformation, sought to reunite the Protestants to the Church of Rome by means of conciliatory measures. His principal works are, Antidi- dagma (against the archbishop Hermann, Cologne, 1544) : — Institutio catholica (1550): — Von wahrer u. blei-bender Gegenwart d. Leibes u. Blutes Christi (1556): — Capita institutionis ad pietatem (1557), etc. — Herzog, Real-Encykl. s.v.; Dieringer, Kathol. Zeitschrift (vol. ii, 1844).