Peter Kropotkin (1842–1921) was perhaps the mildest of all the Marxists and anarchists. He mainly sought to provide a scientific foundation for anarchist-communism by drawing on his own work in geology and his knowledge of Charles Darwin. He was a Russian prince, claimed to be descended from Rurik, who was said to have founded Russia. (Some say Rurik was not an actual historical person, and even if he were it would be hard to prove who his descendants were.)

Kropotkin also wrote the entry for anarchism in the famous eleventh edition of the Encyclopedia Britannica that was published in 1911. This edition was mainly composed by the experts in leadings fields of nineteenth century knowledge and is still highly regarded. (All volumes of this edition are now available free online.)