Raniero Panzieri (1921 – Turin, 9 October 1964) was an Italian politician, writer and Marxist theorist, considered as the founder of operaismo.

Raniero Panzieri is among the main intellectuals who have animated the Italian workers' movement in the sixties. The new intellectual wave known as operaismo focused upon a peculiar interpretation of marxism that theorized the centrality of the working class. This brought about a profound fracture with the traditional left parties, the Italian Communist Party and the Italian Socialist Party which had chosen instead to make their way within the institutions of the State, gradually taking distance from the workers' movement.

Raniero Panzieri, inexhaustible source of ideas for the movement, quit his employment as leader of the Socialist Party in 1959 and moved to Turin to work for Einaudi publishing house. He acted as the glue and coordinator of the groups of young intellectuals living in the main industrial cities in Italy who, in 1961, gathered toghether to give birth to the periodical <Quaderni Rossi> (Red Notebooks).

His main contribution to operaismo consisted in the elaboration of a revolutionary theory which he based on the analysis of the capital and on the study of labour as autonomous and conflictual element. Although he theorized the centrality of the working class and of the workers control of the factory, he did not idealize the strategy of the refusal of work, of the block of production and of the rupture with the historical organizations of the workers movement. In fact, Panzieri put less emphasis on the spontaneity of the working class and  considered the workers politics as the product of the encounter between the working class and socialism. He also assigned the party a specific function at service of the workers movement, and proposed a process of renovation from below through both conflictuality and the formation of new socialist organizations  within the sphere of economic production rather than within the political-institutional sphere.

Panzieri also worked on the marxist idea of the capitalist appropriation of science and technology to increase the capitalist control over economic production. He revealed how the myth of the rationality of science and technology is actually functional to the dynamics of capitalist power that exercises control over production limiting the autonomy of the labour force.