Mariano Ferreyra (3 June 1987, Sarandí, Buenos Aires, Argentina – 20 October 2010, Buenos Aires, Argentina) was an Argentine student who was active in the Workers' Party (Partido Obrero).
He was shot dead during a dispute involving railway workers in Buenos Aires. He was allegedly shot by supporters of a Peronist trade union affiliated to the CGT, in a clash with socialist workers who claimed to end tertiarization. Two other people were injured in the shooting. One, Elsa Rodríguez, a mother of three, was seriously injured and was still fighting for her life in hospital a week later. It is alleged that the police stood by at the time. His death led to widespread protests in Argentina. Thousands marched in Buenos Aires, and the CTA called a general strike in protest.