Karl Marx was born in the German city of Trier in 1818. He studied law in Bonn and Berlin at his father's insistence, but his true interests lay elsewhere and, in 1841, he received a doctorate in philosophy from the University of Jena.

For the next two years he wrote for radical left-wing newspapers before moving to Paris with his wife, Jenny; there he became a communist and met his lifelong friend and collaborator, Friedrich Engels.

They published their revolutionary pamphlet, The Communist Manifesto, in 1848 and Marx moved to London a year later. He spent the rest of his life there - often in considerable poverty - while he wrote his magnum opus of political theory, Das Kapital. Karl Marx died in 1883.

Rosa Luxemburg (1871-1919) was a Polish-born Jewish revolutionary and one of the greatest theoretical minds of the European socialist movement. An activist in Germany and Poland, the author of numerous classic works, she participated in the founding of the German Communist Party and the Spartacist insurrection in Berlin in 1919. She was assassinated in January of that year and has become a hero of socialist, communist and feminist movements around the world.

Peter Kropotkin (1842-1921) came from a major aristocratic Russian family but turned his back on it to embrace a life of imprisonment and exile in pursuit of his beliefs. His major works are The Conquest of Bread and Mutual Aid. His funeral was marked by the last permitted gathering of anarchists in the USSR.