This article revisits the idea of the ‘dictatorship of the proletariat’ in the works of Karl Marx and Friedrich Engels at the hand of the concept of ‘sovereignty’. Proletarian dictatorship was conceptualized, first, in terms of popular sovereignty and of a democracy striking down bourgeois armed rebellions; and, second, in terms of a narrow, class-based sovereignty: a proletarian state placing the bourgeois class as such under a violent, oppressive regime. Marx’s and Engels’ proletarian dictatorship combined two incompatible notions of sovereignty: democratic parliamentarism and ???the proletariat organized as ruling class’ , into a tense ???hybrid sovereignty???. This ambiguous vision is contextualized as a typical nineteenth-century construct and explored for its conceptual coherence and incoherences.