Johann Baptista Baltzer (16 June 1803 – 1 October 1871) was a German Catholic theologian.
He was born at Andernach, studied at Bonn, and after his ordination to the priesthood in 1829, was made professor of theology at Breslau in the following year. He was at first an enthusiastic follower of Georg Hermes in his attempt to reconcile the newer German philosophy with the Roman Catholic teaching, but definitely broke with his school in 1839 and associated himself with the speculations of Anton Günther. After the papal condemnation of the latter's teachings Baltzer submitted indeed, but his independent spirit led him into further difficulties, and he was suspended in 1862.
Baltzer was a strenuous opponent of the definition of papal infallibility and was a promoter of the Old Catholic movement in Silesia. He published Die biblische Schöpfungsgeschichte (two volumes, 1867-73), and Ueber die Anfänge der Organismen (fourth edition, 1869). For his life, consult: Friedberg (Leipzig, 1873), and Meltzer (Bonn, 1877), both favoring Baltzer's attitude, and Franz (Berlin, 1873), representing the other side.