Mariano Moreno (September 23, 1778 – March 4, 1811) was an Argentine lawyer, journalist, and politician. He played a decisive role in the Primera Junta, the first national government of Argentina, created after the May Revolution.
Although he was not prominently involved in the May Revolution that deposed Cisneros, he was appointed as secretary of war of the new government, the Primera Junta. Along with Juan José Castelli, he promoted harsh policies against the supporters of the former government and the strengthening of the new one. These policies were detailed at a secret document, the Operations plan; some historians dispute its authorship. Moreno organized military campaigns to Paraguay and Upper Peru, and ensured the execution of Santiago de Liniers after the defeat of his counter-revolution. He established the first Argentine newspaper, La Gazeta de Buenos Ayres, and translated Jean-Jacques Rousseau's The Social Contract into Spanish.