Johann Baptist Weiss (17 July 1820 in Ettenheim, Baden – 8 March 1899 in Graz) was a German historian.
In 1850 he became editor of the Freiburger Zeitung; in 1852 he became involved in a quarrel with the Government of Baden and, on this account, accepted a call as professor of Austrian history from the University of Graz, where he remained during the years 1853–91.
Weiss wrote the "Geschichte Alfreds des Grossen" (Schaffhausen, 1852), careful but unoriginal; he also issued "Maria Theresa und der österreichische Erbfolgekrieg" (Vienna, 1863).
It extends to the close of the Congress of Vienna and gives special attention to the eighteenth century and the French Revolution, both of which it treats exhaustively on the basis of contemporary literature.
The work is written from a distinctly Roman Catholic point of view and is partisan in its account of the conflict between the Empire and the Papacy in the medieval era, of the Protestant Reformation and the Counter-Reformation, and of the Rationalism of the eighteenth century.