Salvador Cayetano Carpio (August 1919 – 12 April 1983),[1] also known by his nom de guerre Commander Marcial, was a Salvadoran left-wing revolutionary and the Secretary-General of the Communist Party of El Salvador in the 1960s, until his resignation from the party where he then founded the Salvadoran revolutionary political-military organization, the Farabundo Martí Popular Liberation Forces (FPL).

[2] Carpio's founding of the FPL was a result of his belief to end the military dictatorship in El Salvador through an armed revolution.

However, the Salvadoran Communist Party was against armed struggle, instead engaging mainly in legal electoral and trade union organizing.

As a result of various acts of political repression against the left, much of his adult life was spent in prison, in exile or underground.

As the senior leader of the revolutionary movement and commander-in-chief of its largest organization, Carpio was a central figure in the Farabundo Martí National Liberation Front (FMLN).