The chapter provides an overview of Karl Marx's social theory, examining his dialectical groundings, concepts of dehumanisation and humanism, and his theory of historical materialism. It explores Marx's theory of value and systemic collapse, along with his ideas on social classes, the state, and revolution. The chapter further analyses Marx's perspectives on race, ethnicity, and gender in relation to capital and class, while also considering his views on colonialism, globalisation, and revolutionary forces. It reveals how Marx’s thinking evolved over time to appreciate non-Western societies, and it highlights the resurgence of interest in Marx's ideas among contemporary social theorists. The chapter provides an overview of core concepts, including alienation, communism, modes of production, and class struggle, offering a comprehensive assessment of his enduring impact on social theory.