Alexander Aleksandrovich Bogdanov (1873-1928) was a Russian physician, philosopher, science fiction writer, and revolutionary of Belarusian ethnicity. He was a key figure in the early history of the Bolshevik faction of the Russian Social Democratic Labor Party, being one of its cofounders and a rival to Lenin until being expelled in 1909. In the first two decades of the Soviet Union, he was an influential opponent of the government from a Marxist perspective. The polymath Bogdanov received training in medicine and psychiatry. His scientific interests ranged from the universal systems theory to the possibility of human rejuvenation through blood transfusion. He invented an original philosophy called "tectology," now regarded as a forerunner of systems theory. He was also an economist, culture theorist, science fiction writer, and political activist.