Karl Marx (1818-1883) was a German philosopher, economist, and revolutionary socialist who laid the groundwork for modern communism. He co-authored "The Communist Manifesto" with Friedrich Engels, advocating for a classless society where workers control the means of production. Marx's most famous work, "Das Kapital," critiqued capitalism and its exploitation of labor. His ideas have had a profound impact on global politics and continue to influence social movements worldwide.