Karl Marx (1818-1883) was a German philosopher, economist, and political theorist best known for his critique of capitalism and his influential works on socialism and communism. Along with Friedrich Engels, he authored "The Communist Manifesto" (1848), which outlined the principles of communism and called for the proletariat (working class) to overthrow the bourgeoisie (capitalist class). His seminal work, "Das Kapital" (1867), provided a detailed analysis of capitalist economics and its inherent inequalities. Marx's ideas laid the foundation for modern socialism and communism, profoundly influencing political movements and theories worldwide.