Moritz Joseph Josias Lieber (1 October 1790 at the castle of Blankenheim in the Eifel – 29 December 1860 in Bad Camberg, Hesse-Nassau) was a German Catholic politician and publisher.
His earliest literary activity was the translation of prominent Catholic works from foreign tongues, seeking thus to combat the spirit of the Enlightenment and Rationalism which had been rampant in Germany since the days of Joseph II, Holy Roman Emperor.
In answer to the pamphlet Bruchstück eines Gespräches über die Priesterehe (Hadamar, 1831), in which an anonymous "friend of the clergy and of women" attacked the celibacy of the Catholic priesthood, Lieber wrote Vom Cölibat (Frankfurt, 1831).
In his defence he issued under the pseudonym of "A Practical Jurist" the polemic, Die Gefangennehmung des Erzbischofs von Köln und ihre Motive (3 parts, Frankfurt, 1837–38).
He presided at its sessions held in 1849 in Breslau, and in 1867 in Salzburg, the predecessors of the major Catholic congresses, and as president of the Breslau Congress he drew up the protest of the Katholische Verein Deutschlands against the proposals for reform made by the Freiburg professor, J.B. Hirscher, in his work Erörterungen über die grossen religiösen Fragen der Gegenwart (3 parts, Freiburg im Br., 1846–55).