Guillermo León Sáenz Vargas, more commonly known by his nom de guerre Alfonso Cano, was the commander of the militant group known as Revolutionary Armed Forces of Colombia. He succeeded founder Manuel Marulanda in March 2008 and commanded the Marxist rebel group until being killed in action by the Colombian Army.

The military structure of the Fuerzas Armadas Revolucionarias de Colombia – Ejército del Pueblo, formally began to be developed after the middle of 1964, when the Colombian Army occupied the town of Marquetalia.