This document provides biographical information on several influential socialist thinkers and leaders from the 18th-19th centuries including Francois-Noel Babeuf, Robert Owen, Karl Marx, Friedrich Engels, Eduard Bernstein, and Vladimir Lenin. It describes their backgrounds, ideas, and contributions to early socialist movements. Babeuf was an early French revolutionary who advocated for economic equality. Owen established cooperative communities in England and the US. Marx and Engels collaborated on Communist Manifesto and theories of socialism. Bernstein questioned some Marxist beliefs. Lenin helped lead communist revolution in Russia.