Anarchist theorists

Karl Diehl (March 27, 1864, Frankfurt – May 12, 1943 in Freiburg im Breisgau) was a German economist and professor who taught from 1908 until his death in Freiburg. He taught at the universities of Heidelberg and Freiburg, known for teaching on the subject of Anarchism.The motivating force behind his scholarship was that academia must counter the idea that "...anarchism represents a criminal sect which lacks any social or political programme..." According to one historian on German reformers, Diehl had acquired a reputation as the "most important authority on socialism, communism, and anarchism," comparable only to Werner Sombart.

Paul Arthur Müller-Lehning (23 October 1899, in Utrecht – 1 January 2000, in Lys-Saint-Georges) was a Dutch author, historian and anarchist.
Arthur Lehning wrote noted French translations of Mikhail Bakunin. In 1992 he won the Gouden Ganzenveer, and in 1999 the P. C. Hooft Award. In 1976 Arthur Lehning delivered the Huizinga Lecture, under the title: Over vrijheid en gelijkheid (On liberty and equality).

John Henry Mackay (February 6, 1864 – May 16, 1933) was a Scottish-German egoist anarchist, thinker and writer. Born in Scotland and raised in Germany, Mackay was the author of Die Anarchisten (The Anarchists, 1891) and Der Freiheitsucher (The Searcher for Freedom, 1921).
Later in life, under the pseudonym Sagitta, he became an advocate for homosexual love between men and boys.