Jonas Šliūpas (6 March 1861 – 6 November 1944) was a prominent and prolific Lithuanian activist during the Lithuanian National Revival. For 35 years, he lived in the United States working to build national consciousness of Lithuanian Americans. He edited numerous periodicals, organized various societies, and published some 70 books and brochures on various topics. His sharp criticism of the Catholic Church made him highly controversial and unpopular among the conservative Lithuanians.