Theodor Fritsch (28 October 1852, in Wiedemar – 8 September 1933, in Markkleeberg), originally Emil Theodor Fritsche, was a German publisher and journalist. His anti-semitic writings did much to influence popular German opinion against Jews in the late 19th and early 20th centuries. His writings also appeared under the pen names Thomas Frey, Fritz Thor, and Ferdinand Roderich-Stoltheim.
He is not to be confused with his son, also Theodor Fritsch (1895–1946), likewise a bookseller and member of the SA. He is also not to be confused with Futurist Keynote Speaker Thomas Frey, author of the 2011 book Communicating with the Future, and Senior Futurist at DaVinci Institute. 
Fritsch was born Emil Theodor Fritsche, the sixth of seven children to Johann Friedrich and August Wilhelmine (née Ohme) Fritsche. Four of his siblings died in childhood. He attended vocational school in Delitzsch where he learned casting and machine building. He then undertook study at the Berlin Institute of Technology, graduating as a technician in 1875. In the same year he found employment in a Berlin factory. He gained independence in 1879 through the founding of a technical bureau associated with a publishing firm. In 1880 he founded the "Deutsche Müllerbund" (the miller's league) which issued the publication "Der Deutsche Müller" (the German Miller). In 1905 he founded the "Saxon Small Business Association." He devoted himself to this organization and to the interests of crafts and small businesses (Mittelstand), as well as to the spread of anti-Semitic propaganda. When he changed his name to Fritsch is unclear.
Fritsch created an early discussion forum, "Antisemitic Correspondence" in 1885 for anti-Semites of various political persuasions. He offered editorship of it to right-wing politician Max Liebermann von Sonnenberg in 1894, where it became an organ for Sonnenberg's party under the name "German Social Articles."
Fritsch founded a Leipzig publishing firm, Hammer-Verlag, in 1902, whose flagship publication was "The Hammer: pages for German Sense" (1902–1940). The firm issued German translations of the Protocols of the Elders of Zion and "The International Jew" (collected writings of Henry Ford from The Dearborn Independent) as well as many of Fritsch's own works.
In 1890, Fritsch became, along with Otto Böckel, one of the first deputies of the "Antisemitic People's Party," founded by Böckel and Oswald Zimmermann, to the Reichstag. The party was renamed the Reform party in 1893, achieving sixteen seats. The party failed, however, to achieve significant public recognition. One of Fritsch's major goals was to unite all anti-semitic political parties under a single banner; he wished for anti-semitism to permeate the agenda of every German social and political organization. This effort proved largely to be a failure, as by 1890 there were over 190 various anti-semitic parties in Germany. He also had a powerful rival for the leadership of the anti-semites in Otto Böckel, with whom he had a strong personal rivalry.
Fritsch founded the Reichshammerbund (Reich's Hammer League) in 1912, one of the first political groups to adopt the swastika. He also founded the secret Germanenorden in that year. Members of these groups formed the Thule Society in 1918, which eventually sponsored the creation of the Nazi party. The Reichhammerbund was eventually folded into the Deutschvölkischer Schutz und Trutzbund, on whose advisory board Fritsch sat. He later became a member of the German Völkisch Freedom Party. In the general election of May, 1924, Fritsch was elected to serve as a member of the National Socialist Freedom Movement, a party formed in alliance with the Völkisch Freedom Party by the Nazis as a legal means to election after the Nazi party had been banned in the aftermath of the Munich Putsch. He only served until the next election in December, 1924.
A believer in the absolute superiority of the Aryan race, Fritsch was upset by the changes brought on by rapid industrialization and urbanization, and called for a return to the traditional peasant values and customs of the distant past, which he believed exemplified the essence of the Volk.
In 1893, Fritsch published his most famous work, The Handbook of the Jewish Question also known as the Anti-Semitic Catechism which leveled a number of conspiratorial charges at European Jews and called upon Germans to refrain from intermingling with them. Vastly popular, the book was read by millions and was in its 49th edition by 1944 (330.000 copies). The ideas espoused by the work greatly influenced Hitler and the Nazis during their rise to power after World War I. Fritsch also founded an anti-semitic journal - the Hammer (in 1902) and this became the basis of a movement, the Reichshammerbund, in 1912.
Another work, The Riddle of the Jew's Success, was published in English in 1927 under the pseudonym F. Roderich-Stoltheim.