José Eduardo Sancho Castañeda (born 6 March 1947), better known by his nom de guerre Fermán Cienfuegos, was the leader of the Salvadoran organization National Resistance Armed Forces (FARN), which was a part of National Resistance (RN).

His parents met in El Salvador in 1942 when Sancho Colombari went to the country to study medicine.

[2] Sancho Castañeda was influenced by leftists in Costa Rica, including Manuel Mora Valverde, the leader of the People's Vanguard Party whom he considered to be a close friend.

He opposed the Football War fought between the governments of El Salvador and Honduras in 1969.

In 1980, the RN was one of the five revolutionary Marxist organizations that formed the Farabundo Martí National Liberation Front (FMLN) that fought an armed struggle against the Salvadoran government.